GENERAL STATEMENT OF THE CLASS SUBJECT MATTER
This is the generic class for electrical apparatus and corresponding methods for performing calculation operations.
SCOPE OF THE CLASS
(1) Note. This class is limited to electrical and calculating computer apparatus and corresponding methods wherein a calculation operation is performed on information carried by wave propagation (either electromagnetic or compressional waves) provided that input to and output from the apparatus is electrical. Note: where the apparatus performing the calculation operation is electrically responsive but the data is not presented to and output from the apparatus as electrical signals, classification is with the appropriate wave energy subject matter, as per one of the optical classes.
(2) Note. Significantly claimed apparatus external to this class, claimed in combination with apparatus under the class definition, which perform data processing or calculation operations are classified in the class appropriate to the external device unless specifically excluded therefrom.
(3) Note. Nominally claimed apparatus external to this class in combination with apparatus under the class definition is classified in this class unless provided for in the appropriate external class.
THIS CLASS IS STRUCTURED INTO THREE MAIN DIVISIONS:
A. Electrical Hybrid Calculating Computers
B. Electrical Digital Calculating Computers
C. Electrical Analog Calculating Computers

REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:
235, Registers, various subclasses for basic machines and associated indicating mechanisms for ascertaining the number of movements of various devices and machines, plus machines made from these basic machines alone (e.g., cash registers, voting machines)or in combination with various perfecting features, such as printers and recording means, as well as for various data bearing record controlled systems.
307, Electrical Transmission or Interconnection Systems, various subclasses for generic residual electrical
transmission or interconnection systems and miscellaneous circuits.
326, Electronic Digital Logic Circuitry, various subclasses for digital logic devices.
327, Miscellaneous Active Electrical Nonlinear Devices, Circuit, and Systems, various subclasses for miscellaneous active device analog circuits.
340, Communications: Electrical, various subclasses for residual electrical communication systems.
341, Coded Data Generation or Conversion, various subclasses for electrical pulse and digital code converters.
345, Computer Graphics Processing, Operator Interface Processing, and Selective Visual Display Systems, various subclasses for the selective control of two or more light generating or light controlling display elements in accordance with a received image signal.
359, Optics: Systems (Including Communication) and Elements, subclasses 107+ for optical computing without diffraction and subclasses 237+ for optical modulators.
360, Dynamic Magnetic Information Storage or Retrieval, appropriate subclasses for record carriers and systems wherein information is stored and retrieved by interaction with a medium and there is relative motion between a medium and a transducer, for example, magnetic disk drive devices and control thereof, per se.
361, Electricity: Electrical Systems and Devices, subclasses 679+ for housing or mounting of electronic device or system which may provide keyboard or computer support.
364, Electrical Computers and Data Processing Systems, subclasses 130+ for data processing control systems, subclasses 400+ for particular application of electrical computers and data processing systems.
365, Static Information Storage and Retrieval, various subclasses for addressable static singular storage elements or plural singular storage elements of the same type.
369, Dynamic Information Storage or Retrieval, various subclasses for record carriers and systems wherein information is stored and retrieved by interaction with a medium and there is relative motion between a medium and a transducer.
370, Multiplex Communications, various subclasses for generic multiplexing and demultiplexing systems.
375, Pulse or Digital Communications, various subclasses for generic pulse or digital communication systems.
377, Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, various subclasses for generic circuits for pulse counting.
379, Telephonic Communications, various subclasses for two-way electrical communication of intelligible audio information of arbitrary content over a link including an electrical conductor.
382, Image Analysis, appropriate subclasses for operations performed on image data with the aim of measuring a characteristic of an image, detecting variations, detecting structures, or transforming the image data, and for procedures for analyzing and categorizing patterns present in image data.
395, Information Processing System Organization, subclasses 80+ for robot control, subclasses 101+ for static data presentation processing, and subclasses 500 and 527 for simulation, emulation, or compatability of system components.
701, Data Processing: Vehicles, Navigation, and Relative Location, appropriate subclasses for vehicular or navigational data processing.
702, Data Processing: Measuring, Calibrating, and Testing, appropriate subclasses for measuring or testing data processing.
704, Data Processing: Speech Signal Processing, Linguistics, Language Translation, and Audio Compression/Decompression for speech, language or audio compression/decompression processing.
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, appropriate subclasses for data processing related to business, finances, management, or cost/price determining.
706, Data Processing: Artificial Intelligence, appropriate subclasses for processing of artificial intelligence.
707, Data Processing: Databases and File Management, Data Structures, and Document Processing appropriate subclasses for database structure, database/file management, or document processing.
709, Electrical Computers and Digital Processing Systems: Multiple Computer or Process Coordinating, appropriate subclasses for computers and digital processing related to plural computers or plural process coordinating.
710, Electrical Computers and Digital Processing Systems: Input/Output, appropriate subclasses for input/output processing (e.g., bus processing) in a computer or digital
data processing system.
711, Electrical Computers and Digital Processing Systems: Memory, appropriate subclasses for storage accessing, control, or addressing in a computer or digital processing system.
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing (e.g., Processors), appropriate subclasses for computer or digital processing system architecture or instruction processing.
713, Electrical Computers and Digital Processing Systems: Support, appropriate subclasses for computer or digital processing system support ( e.g., security, power supply, and timing, etc. )
714, Error Detection/Correction and Fault Detection/Recovery, appropriate subclasses for error or fault detection or compensation in a computer or digital processing system.
III
CALCULATION OPERATIONS
Arithmetic or some limited logic operations performed upon or with signals representing numbers or values. These include arithmetic and related logic operations. A related logic operation is one that is associated with arithmetic computations.
DISCRETE ELECTRICAL SIGNAL
Discontinuous signals which can assume only a finite number of states.
NUMERICAL DIGITS
Symbols that represent a specific quantity or amount of units.

ELECTRICAL HYBRID CALCULATING COMPUTER:
This subclass is indented under the class definition. Subject matter wherein a calculation operation is performed either simultaneously or sequentially upon at least one analog and at least one digital signal or wherein either the analog or digital signal is involved in a calculation operation on the other signal.
(1) Note. This subclass does not include the mere
conversion from one signal format to another, which conversion has no part in the above calculation operation.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 100+ for electrical digital calculating computers.
subclasses 800+ for electrical analog calculating computers.

Plural complete computers:
This subclass is indented under subclass 1. Subject matter which includes at least one complete analog computer and one complete digital computer.

Particular function performed:
This subclass is indented under subclass 1. Subject matter directed to a particular function performed by hybrid computer or subcombination thereof in making computation.
(1) Note. For classification herein, the function performed must be significantly claimed in making a computation.

Evaluation of trigonometric function:
This subclass is indented under subclass 3. Subject matter wherein the function performed is the processing of signal to either determine a trigonometric relationship or to operate on a signal in accordance with a trigonometric relationship.

SEE OR SEARCH THIS CLASS, SUBCLASS:
440 and 811+ for electrical digital or electrical analog computers which perform the function of evaluation of trigonometric functions.

Correlation, convolution, or transformation:
This subclass is indented under subclass 3. Subject matter wherein the function performed is cross-correlation, autocorrelation, cross-convolution, autoconvolution or transforming a given representation of a data signal to another representation without loss of information by an orthogonal transformation.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 400+ 420+, 422+, 813+, and 820+ for electrical digital or analog computers which perform the function of correlation, convolution or transformation.

Integration or differentiation:
This subclass is indented under subclass 3. Subject matter wherein the function performed is integration or differentiation of at least one of a plurality of input signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:
443 and 444, for electrical digital calculating differentiation and integration, respectively computers which perform.
822 and 823+, for electrical analog computers which perform differentiation and integration, respectively.

Multiplication or division:
This subclass is indented under subclass 3. Subject matter wherein the function performed is multiplication or division to produce a product or quotient from at least two input signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 620+ and 650+, for electrical digital computers for performing the function of multiplication or division.
subclasses 835+ and 844, for electrical analog computers for performing the function of multiplication or division.

Function generation:
This subclass is indented under subclass 3. Subject matter wherein the function performed is the generation of at least one signal by mathematical operation or as part of a mathematical operation generates a signal representing a function of at least one variable input parameter.
(1) Note. This subclass includes a waveform synthesizer wherein the waveform is internally generated.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 270+ and 845+, for electrical digital or electrical analog computers which perform the function of function generation.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 100+ for miscellaneous signal converting, shaping, or generating circuits.

Piece-wise linear synthesis:
This subclass is indented under subclass 8. Subject matter wherein the desired function is approximated by a series of segments of straight lines.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 846+ for analog computer piece-wise linear synthesis.

ELECTRICAL DIGITAL CALCULATING COMPUTER:
This subclass is indented under the class definition. Subject matter wherein a calculation operation is performed upon discrete electrical signals representing a value normally described by numerical digits.
(1) Note. The value described includes a value represented by a pulse repetition rate.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 1+ for electrical hybrid calculating computers.
subclasses 800+ for electrical analog calculating computers.

SEE OR SEARCH CLASS:
326, Electronic Digital Logic Circuitry, appropriate subclasses for digital logic devices.

Pulse repetition rate:
This subclass is indented under subclass 100. Subject matter wherein quantities are determinable from the pulse repetition frequency of the discrete electrical signal.

SEE OR SEARCH CLASS:
341, Coded Data Generation or Conversion, subclasses 54+ for digital conversion where a bit is represented by a discrete frequency.

Digital differential analyzer:
This subclass is indented under subclass 101. Subject matter utilized as a digital differential analyzer.

SEE OR SEARCH THIS CLASS, SUBCLASS:
804 for analog differential analyzers.

Multiplication or division:
This subclass is indented under subclass 101. Subject matter wherein the operation performed on an electrical signal is multiplication or division.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 113+ for miscellaneous frequency control.
332, Modulators, subclasses 112+ for pulse frequency modulators.
377, Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, appropriate subclasses for pulse dividing and multiplying circuits.

Plural complete computers:
This subclass is indented under subclass 100. Subject matter which includes at least two complete digital computers.

SEE OR SEARCH THIS CLASS, SUBCLASS:
2 for a hybrid computer formed from plural complete computers.

SEE OR SEARCH CLASS:
364, Electrical Computers and Data Processing Systems, subclasses 131+, for plural programmable computers used in a control system.

Combined with diverse art device:
This subclass is indented under subclass 100. Subject matter which includes a diverse art device having a noncalculating function, with common structure utilized in performing the calculating and the noncalculating functions, or an integrated unit into which the computer and diverse art device are embodied.
(1) Note. Search the art area of the diverse device for the details of the diverse device which are claimed.

Checkbook:
This subclass is indented under subclass 105. Subject matter where the diverse device is a checkbook.

SEE OR SEARCH CLASS:
283, Printed Matter, subclass 58 for banking checks, per se.

Writing instrument (e.g., pen):
This subclass is indented under subclass 105. Subject matter where the diverse device is utilized for a hand-held marking purpose.

SEE OR SEARCH CLASS:
401, Coating Implements With Material Supply, appropriate subclasses for pens or pencils, per se.

Tape recorder:
This subclass is indented under subclass 105. Subject matter where the diverse device is a tape recorder.

SEE OR SEARCH CLASS:
360, Dynamic Magnetic Information Storage or Retrieval, appropriate subclasses, for detail of a magnetic tape recorder, per se.

Communication device (e.g., telephone, radio, television):
This subclass is indented under subclass 105. Subject matter where the diverse device transfers information between distant points.

SEE OR SEARCH CLASS:
348, Television, subclass 552 for particular television structure combined with a calculator.
379, Telephonic Communications, subclass 110.01 for particular telephonic substation structure combined with a calculator.
455, Telecommunications, subclasses 344+ for particular receiver or analog modulated signal frequency converter structure combined with a calculator.

Business device (e.g., billing, memorandum):
This subclass is indented under subclass 105. Subject matter where the diverse device is used in the conducting of trade.
(1) Note. Typical of subject matter found here would be a calculator of generic utility combined with a customer billing device.

SEE OR SEARCH CLASS:
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, appropriate subclasses for data processing systems exclusively designed for or utilized in a business environment.

Horological device:
This subclass is indented under subclass 105. Subject matter where the diverse device measures or indicates time.

SEE OR SEARCH CLASS:
368, Horology: Time Measuring Systems or Devices, subclass 10 for a nominal digital calculating computer in combination with a horological device.

Calendar:
This subclass is indented under subclass 111. Subject matter where the horological device provides indication of a day of the week or a date.

SEE OR SEARCH CLASS:
368, Horology: Time Measuring Systems or Devices, subclasses 28+ for a calendar indicator, per se.

Programmable calculator:
This subclass is indented under subclass 100. Subject matter which includes a calculator that is programmable.
(1) Note. Calculator does not include general purpose computers but is restricted to the limited capacity calculator such as desk calculator or a pocket calculator.

SEE OR SEARCH CLASS:
713, Electrical Computers and Digital Processing Systems: Support, subclass 321 for a programmable calculator with power saving feature.

Having specialized input:
This subclass is indented under subclass 100. Subject matter with specialized input in conjunction with calculation portion.
(1) Note. For classification herein, the calculating portion must be a significant component and the input to the calculating portion must be more than nominally recited.

SEE OR SEARCH CLASS:
200, Electricity: Circuit Makers and Breakers, subclass 5 for a multiple switch assembly, per se.
235, Registers, subclasses 145+ for keyboards.
341, Coded Data Generation and Conversion, subclasses 22+ for a keyboard controlled code transmitting device.
345, Computer Graphics Processing, Operator Interface Processing, and Selective Visual Display Systems, subclasses 156+ for display peripheral interface input device.
348, Television, subclass 552 for video input devices for computers.
710, Electrical Computers and Digital Processing Systems: Input/Output, appropriate subclasses for input/output and bus data processing.

Having supplemental environment related input:
This subclass is indented under subclass 131. Subject matter where input unique to a particular art area can be provided in addition to normal calculator input.
(1) Note. Typically found here is non-numeric environment related input.

Cooking:
This subclass is indented under subclass 132. Subject matter where the supplemental input relates to the preparation of food for consumption.
(1) Note. Typical of subject matter found here is nonnumeric input designating a particular food to be cooked.

SEE OR SEARCH CLASS:
99, Foods and Beverages: Apparatus, subclasses 324+ for particular cooking apparatus.

Business:
This subclass is indented under subclass 132. Subject matter where the supplemental input relates to the conduct of trade.

SEE OR SEARCH CLASS:
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, appropriate subclasses for data processing systems exclusively designed for or utilized in a business environment.

For security:
This subclass is indented under subclass 131. Subject matter where a specialized input controls accessing of the calculating computer.

Input verification:
This subclass is indented under subclass 131. Subject matter where the specialized input provides a check of intended versus actual input.

Fraction input:
This subclass is indented under subclass 131. Subject matter where the specialized input permits entry of a fraction.

Flexible input:
This subclass is indented under subclass 131. Subject matter in which some portion of the input is made nonrigid to facilitate data entry.

Including specific computing system interconnection:
This subclass is indented under subclass 131. Subject matter for specific structure within the specialized input serving as an interface between the device actually manipulated by the operator and computing circuitry.
(1) Note. Included here would be keyboard input which includes specific structure linking the keyboard, per se, with computing circuitry, for example.

Modular or overlay:
This subclass is indented under subclass 131. Subject matter where plug-in modules or overlays are utilized to effect data input.

Including specific nonkeyboard-type information entry:
This subclass is indented under subclass 131. Subject matter where information ultimately conveyed to the calculating portion is produced by a particular device not having plural individually actuatable keys.

Including specific keyboard-type information entry:
This subclass is indented under subclass 131. Subject matter where information ultimately conveyed to the calculating portion is produced by a particular device having plural individually actuatable keys.

SEE OR SEARCH CLASS:
200, Electricity: Circuit Makers and Breakers, appropriate subclasses for switches, per se.
341, Coded Data Generation or Conversion, subclasses 22+ for a keyboard controlled code transmitting device.
345, Computer Graphics Processing, Operator Interface Processing, and Selective Visual Display Systems, subclasses 168+ for display peripheral interface input device including keyboard.

Nonmechanical key actuation:
This subclass is indented under subclass 142. Subject matter where input keys are operated by other than a push and release sequence (e.g., magnetic activation).

SEE OR SEARCH CLASS:
335, Electricity: Magnetically Operated Switches, Magnets, and Electromagnets, appropriate subclasses for magnetic switches, per se.
337, Electricity: Electrothermally or Thermally Actuated Switches, appropriate subclasses for thermal switches per se.

User definable key:
This subclass is indented under subclass 142. Subject matter in which the user defines the function associated with a keyboard key.

SEE OR SEARCH CLASS:
345, Computer Graphics Processing, Operator Interface Processing, and Selective Visual Display Systems, subclass 172 for a display peripheral keyboard having a programmable function key.

Plural function key:
This subclass is indented under subclass 142. Subject matter where a keyboard key has plurality of selectable predetermined functions associated with it.

Key sequencing (i.e., sequence defines function):
This subclass is indented under subclass 142. Subject matter where the order in which a plurality of keys is actuated determines the function to be performed.

Having specialized output:
This subclass is indented under subclass 100. Subject matter with specialized output in conjunction with calculating portion.
(1) Note. For classification herein, the calculating portion must be a significant component and the output from the calculating portion must be more than nominally recited.

SEE OR SEARCH CLASS:
340, Communication: Electrical, subclass 815.4 for visual indicators.
345, Computer Graphics Processing, Operator Interface Processing, and Selective Visual Display Systems, appropriate subclasses for selective visual display systems and computer graphics processing.
710, Electrical Computers and Digital Processing Systems: Input/Output, appropriate subclasses for input/output and bus
data processing.

Having supplemental environment related output:
This subclass is indented under subclass 160. Subject matter where output unique to a particular art area can be provided in addition to normal calculator output.
(1) Note. Typically found here is non-numeric environment related output.

Teaching:
This subclass is indented under subclass 161. Subject matter where the supplemental output relates to education.

SEE OR SEARCH CLASS:
434, Education and Demonstration, appropriate subclasses for instructional devices, per se.

Business:
This subclass is indented under subclass 161. Subject matter where the supplemental output relates to the conduct of trade.

SEE OR SEARCH CLASS:
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, appropriate subclasses for data processing systems exclusively designed for or utilized in a business environment.

Output verification:
This subclass is indented under subclass 160. Subject matter in which the output is provided in a form permitting checking thereof (e.g., trace).

Blanking:
This subclass is indented under subclass 160. Subject matter where the specialized output has provision for suppressing a selected portion of the output.

Zero suppression:
This subclass is indented under subclass 165. Subject matter wherein the blanking means has zero suppression capability.

Prompting:
This subclass is indented under subclass 160. Subject matter where the specialized output provides the user with guidance regarding future information entry.

Selective output:
This subclass is indented under subclass 160. Subject matter where the specialized output permits choosing the desired output from a plurality of candidates.

SEE OR SEARCH THIS CLASS, SUBCLASS:
174 for multiple simultaneous outputs.

Sequential output:
This subclass is indented under subclass 160. Subject matter where the specialized output provides successive portions of a desired output one at a time.

Using particular format:
This subclass is indented under subclass 160. Subject matter where the specialized output provides the output in a specified form.
(1) Note. The particular format might be engineering notation or floating point, for example.

Symbol accompanying output:
This subclass is indented under subclass 160. Subject matter in which the specialized output provides a special symbol with the output representation.

Audio:
This subclass is indented under subclass 160. Subject matter where the specialized output is in audible form.

SEE OR SEARCH CLASS:
364, Electrical Computers and Data Processing Systems, subclasses 131+, for plural programmable computers used in a control system.
381, Electrical Audio Signal Processing Systems and Devices, appropriate subclasses for electrical audio signal processing in general.

Printer:
This subclass is indented under subclass 160. Subject matter in which the specialized output provides the output representation in permanent readable form.

SEE OR SEARCH CLASS:
347, Incremental Printing of Symbolic Information, appropriate subclasses for incremental printing (e.g., ink jet printing).
395, Information Processing System Organization, subclasses 101+ for static presentation processing (e.g., for a printer).

Multiple simultaneous outputs:
This subclass is indented under subclass 160. Subject matter where a plurality of output representations are made available by the specialized output at the same time.

SEE OR SEARCH THIS CLASS, SUBCLASS:
168 for selective output.

Integrated circuit:
This subclass is indented under subclass 100. Subject matter wherein the calculating is effected by an integrated circuit or chip, the use or specific structure or arrangement of which significantly affects or directs the handling of information.

SEE OR SEARCH CLASS:
257, Active Solid-State Devices (e.g., Transistors, Solid-State Diodes), appropriate subclasses for integrated circuit structure with active solid-state devices, subclass 446 and 499+ for integrated circuit devices with electrically isolated components, in general, and other appropriate subclasses for specific type devices in integrated circuits.
326, Electronic Digital Logic Circuitry, subclasses 101+ for electronic logic with significant integrated structure.
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 564+ for miscellaneous circuits with integrated structure.

Electro-optical:
This subclass is indented under subclass 100. Subject matter wherein the calculating is effected by electro-optical devices.

SEE OR SEARCH CLASS:
359, Optics: Systems (Including Communication) and Elements subclasses 107+ for optical computing without diffraction
and subclasses 237+ for optical modulators.

Bubble-domain:
This subclass is indented under subclass 100. Subject matter wherein the calculating is effected by bubble-domain devices.

SEE OR SEARCH CLASS:
365, Static Information Storage and Retrieval, subclasses 1+ for magnetic bubble-domain devices used for storage of information.

Particular function performed:
This subclass is indented under subclass 100. Subject matter having a particular function involving a calculation performed by digital computer or subcombination thereof.
(1) Note. For classification herein, the calculating performed in effecting the function must be significantly claimed.

SEE OR SEARCH CLASS:
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing ( e.g., Processors) subclasses 1+ for particular processing architecture which could be utilized in performing the particular function.

Absolute value or magnitude:
This subclass is indented under subclass 200. Subject matter wherein the particular function determines the absolute value or magnitude of a result from an arithmetic operation.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclass 354 for a specific input-to-output function performed by an absolute value.

Median:
This subclass is indented under subclass 200. Subject matter wherein the particular function provides the middle value in a series.

Compression/decompression:
This subclass is indented under subclass 200. Subject matter for representing a number or group of numbers by a smaller number of digits than that possessed originally or the inverse operation.

SEE OR SEARCH CLASS:
341, Coded Data Generation or Conversion, subclass 60 for digital conversion to or from a packed format.
348, Television, subclasses 384+ for a bandwidth reduction system.
382, Image Analysis, subclasses 232+ for data compression in an image processing system.
709, Electrical Computer and Digital Processing Systems: Multiple Process or Process Coordinating subclasses 247+ for data compressing/decompressing in computer data transfer.

Format conversion:
This subclass is indented under subclass 200. Subject matter for changing a number having a representation in one form to a representation in another form.

SEE OR SEARCH CLASS:
341, Coded Data Generation or Conversion, subclasses 50+ for digital-to-digital converters.

Normalization:
This subclass is indented under subclass 204. Subject matter in which the number in final form includes a single nonzero digit to the left of a radix point.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 495+ for floating point systems.

Unit conversion:
This subclass is indented under subclass 200. Subject matter where a number reflecting a first system of measurement is changed to reflect a second system of measurement.
(1) Note. Included here are such conversions as English to metric.

Maximum/minimum determination:
This subclass is indented under subclass 200. Subject matter in which the largest or smallest of a group of numbers is found.

Scaling:
This subclass is indented under subclass 200. Subject matter where a number is modified by a predetermined multiplicative factor.

Shifting:
This subclass is indented under subclass 200. Subject matter where a number is changed by moving each digit therein simultaneously a specified number of positions in a specified direction.
(1) Note. Digits that are shifted beyond the confines of the number may or may not be recirculated into the opposite end of the number. Fixed digits may be inserted there
instead.

SEE OR SEARCH CLASS:
377, Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and systems, appropriate subclasses for shift registers.
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing (e.g., Processors), subclass 898 for byte word order rearranging.

Determining number of like-valued bits in word:
This subclass is indented under subclass 200. Subject matter where the number of 1's or the number of 0's in a binary word is determined.

Determining number of like-valued leading or trailing bits:
This subclass is indented under subclass 200. Subject matter where the number of consecutive leading or trailing 1's or 0's in a binary word is determined.

Detecting particular sequence of bits:
This subclass is indented under subclass 200. Subject matter for locating a particular string of bits in a larger string of bits.

SEE OR SEARCH CLASS:
375, Pulse or Digital Communications, subclasses 354+ for synchronizers, per se.
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing (e.g., Processors), subclass 898 for byte-word sequence detecting.

Multifunctional:
This subclass is indented under subclass 200. Subject matter wherein the electric digital calculating computer provides for selectively performing at least one logical operation as well as at least one arithmetical operation relative to operands (e.g., a programmable logic circuit with computational means).

SEE OR SEARCH CLASS:
307, Electrical Transmission or Interconnection Systems, subclasses 407+ for nonlinear reactor logic circuits.
326, Electronic Digital Logic Circuitry, subclasses 37+ for programmable logic circuits not performing arithmetic calculations and which are typically solid state.
365, Static Information Storage and Retrieval, appropriate subclasses for programmable logic circuits which include storage and retrieval of information.

Microprocessor:
This subclass is indented under subclass 230. Subject matter wherein the multifunctional operation is performed by a microprocessor.

SEE OR SEARCH THIS CLASS, SUBCLASS:
303 for a particular microprocessor used in a filtering operation.
510 for a particular microprocessor used in floating point.

SEE OR SEARCH CLASS:
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing (e.g., Processors), subclasses 32+ for particular microprocessor architecture.

Array of elements (e.g., AND/OR array, etc.):
This subclass is indented under subclass 230. Subject matter wherein the multifunctional operation is performed by a group of many similar, basic, complex, or integrated elements without separated enclosures, such as AND/OR arrays, etc.

Pipeline:
This subclass is indented under subclass 230. Subject matter wherein the multifunctional operation is performed in a pipeline where the output of one task is input to another until a desired sequence of tasks has been carried out.

SEE OR SEARCH THIS CLASS, SUBCLASS:
406 for Fourier transformation performed in a particular pipeline.
508 for floating point performed in a particular pipeline.
521 for arithmetical pipeline operation in general.
631 for multiple digit binary multiplication performed in a particular pipeline.

Parallel bit input of operand:
This subclass is indented under subclass 230. Subject matter wherein the multifunctional operation is performed in bit level and the bits of operands are input in parallel.

Uses look-up table:
This subclass is indented under subclass 230. Subject matter wherein the operation involves a look-up table to search for a desired item of information.

More than two operands:
This subclass is indented under subclass 230. Subject matter wherein the operations involve three or more operands.

Random number generation:
This subclass is indented under subclass 200. Subject matter
wherein the computer generates a number or sequence of numbers characterized by unpredictability so that no number is any more likely to occur at a given time or place in a sequence than any other.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclass 164 for a miscellaneous circuit producing a rectangular waveform having a random characteristic (e.g., random width).
331, Oscillators, subclass 78 for electrical noise or random wave generation by oscillators (e.g., random pulse generators).

Oscillator controlled:
This subclass is indented under subclass 250. Subject matter wherein the generation is effected by an oscillator or clock.

Linear feedback shift register:
This subclass is indented under subclass 250. Subject matter wherein the generation is performed by a feedback shift register in which a proportional relationship exists between an input and output.

SEE OR SEARCH CLASS:
377, Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, appropriate subclasses for a shift register, per se.

Plural parallel output bits:
This subclass is indented under subclass 250. Subject matter wherein the generation produces plural bits of a sequence in parallel.

SEE OR SEARCH THIS CLASS, SUBCLASS:
256 for plural parallel outputs.

Seed value controls:
This subclass is indented under subclass 250. Subject matter wherein seed value is used as an initial value in the generation.

Truly random number:
This subclass is indented under subclass 250. Subject matter wherein the generation produces a random sequence which is not repeated.

Plural parallel outputs:
This subclass is indented under subclass 250. Subject matter wherein the generation produces plural sequences in parallel.

SEE OR SEARCH THIS CLASS, SUBCLASS:
253 for plural parallel output bits.

Function generation:
This subclass is indented under subclass 200. Subject matter wherein a sequence of discrete values is generated to represent a desired waveform.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 8+ and 845+, for electrical hybrid or electrical analog computers which perform the function of function generation.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 100+ for miscellaneous signal converting, shaping, or generating circuits.

Direct digital frequency synthesizer:
This subclass is indented under subclass 270. Subject matter wherein the generation is performed by a digital frequency source capable of producing a multitude of output frequencies from the desired frequency of the waveform.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 105+ for a synthesizer converting, shaping, or generating a nonlinear signal.

Memory used to store waveshape:
This subclass is indented under subclass 270. Subject matter wherein a circuit allows a waveshape to be stored and retrieved for generating the waveform.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclass 106 for waveform or waveshape determinative circuits including stored data.

Counter as source (i.e., input):
This subclass is indented under subclass 270. Subject matter wherein a circuit counts input pulses for producing phase increments as a source.

Linear:
This subclass is indented under subclass 270. Subject matter where the desired waveform is linear.

SEE OR SEARCH THIS CLASS, SUBCLASS:
8 for a hybrid computer providing piece-wise linear synthesis.
852 for analog triangular, sawtooth or ramp function generation.

Circular:
This subclass is indented under subclass 270. Subject matter where the desired waveform represents a circular relationship.

Trigonometric:
This subclass is indented under subclass 270. Subject matter where the desired waveform has trigonometric relationships.

Logarithmic/exponential:
This subclass is indented under subclass 270. Subject matter where the desired waveform is logarithmic or exponential.

SEE OR SEARCH THIS CLASS, SUBCLASS:
851 for analog logarithmic/exponential function generation.

Interpolation/extrapolation:
This subclass is indented under subclass 200. Subject matter for the determination or estimation of a value or values of a function between two known values or of the trend established between two or more known points.

SEE OR SEARCH THIS CLASS, SUBCLASS:
313 for decimation/interpolation in digital filtering.
847 for interpolation/extrapolation in analog piece-wise linear function synthesis.

SEE OR SEARCH CLASS:
318, Electricity: Motive Power Systems, subclass 573 for
interpolation in positional servo systems.

Filtering:
This subclass is indented under subclass 200. Subject matter wherein a computational process or algorithm separates data, signals, or materials in accordance with specified criteria.

SEE OR SEARCH THIS CLASS, SUBCLASS:
819 for analog computer filtering.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 551+ for miscellaneous unwanted signal suppression utilizing an active filter circuit not performing an arithmetic calculation.
702, Data Processing: Measuring, Calibrating, or Testing, subclasses 190+ for signal extraction or separation in measured signal processing.

Tapped delay line:
This subclass is indented under subclass 300. Subject matter wherein a delay line, in which more than two terminal pairs are associated with a single delay channel, is used to provide delayed signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:
425 for correlation using tapped delay line.

Microprocessor:
This subclass is indented under subclass 300. Subject matter wherein the filtering is performed by a microprocessor.

SEE OR SEARCH THIS CLASS, SUBCLASS:
231 for a particular microprocessor used in the multifunctional operation.
510 for a particular microprocessor used in floating point.

SEE OR SEARCH CLASS:
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing (e.g., Processors) subclasses 32+ for particular microprocessor architecture.

Nonlinear (e.g., median, etc.):
This subclass is indented under subclass 300. Subject matter wherein the relationship between the pertinent measures of the input and output signals cannot be adequately described by linear means (e.g., median filter).

SEE OR SEARCH CLASS:
382, Image Analysis, subclass 262 for a median image filter.

Initialization:
This subclass is indented under subclass 300. Subject matter where the filter is placed in a beginning state prior to the actual processing.

Finite arithmetic effect:
This subclass is indented under subclass 300. Subject matter for indication or compensation of an effect arising from the use of operands having a finite length representation.
(1) Note. Included here are such effects as overflow, underflow and oscillation.

SEE OR SEARCH THIS CLASS, SUBCLASS:
496 for floating point compensation for finite word length.

Delta/differential coded:
This subclass is indented under subclass 300. Subject matter in which the samples used in processing are present in the delta or differential coded format.

SEE OR SEARCH CLASS:
341, Coded Data Generation or Conversion, subclasses 76+ for digital conversion to or from a differential code.

Multidimensional data:
This subclass is indented under subclass 300. Subject matter where the data to be processed is multidimensional (e.g., image data).

SEE OR SEARCH CLASS:
382, Image Analysis, subclasses 254+ for image enhancement which may include filtering.

Frequency measurement:
This subclass is indented under subclass 300. Subject matter where frequency determination is accomplished by first removing from a signal corrupting noise which was imposed by a transmission medium.

SEE OR SEARCH CLASS:
324, Electricity: Measuring and Testing, subclass 76.39 for frequency measurement of cyclic current or voltage in general.
702, Data Processing: Measuring, Calibrating, or Testing subclasses 75+ for electrical frequency measurement, per se.

Coherent:
This subclass is indented under subclass 300. Subject matter where a particular frequency is eliminated from a signal.

Frequency detection:
This subclass is indented under subclass 300. Subject matter in which a subset of frequencies from a known set of possible frequencies is determined to be present.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 39+ for discriminating by frequency.

Tone detection:
This subclass is indented under subclass 310. Subject matter where the subset consists of a single frequency.

Decimation/interpolation:
This subclass is indented under subclass 300. Subject matter where the filter deletes from or adds to the samples input to it in a specified regular fashion resulting in a net sampling rate change.

SEE OR SEARCH THIS CLASS, SUBCLASS:
290 for interpolation, per se.

Matched filter type:
This subclass is indented under subclass 300. Subject matter for maximizing the signal-to-noise ratio through the use of filters utilizing correlation techniques.

SEE OR SEARCH CLASS:
375, Pulse or Digital Communications, subclass 343 for pulse demodulation or detection by matched filters.

By convolution:
This subclass is indented under subclass 300. Subject matter in which a convolution technique is utilized to accomplish the filtering.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 420+ for digital convolution, per se.

Having multiplexing:
This subclass is indented under subclass 300. Subject matter where one of a plurality of signals is selected and processed by a given filter or one of a plurality of filters is selected to process a given signal.

Wave:
This subclass is indented under subclass 300. Subject matter in which the filter has elements representing distributed parameters.

SEE OR SEARCH CLASS:
333, Wave Transmission Lines and Networks, subclasses 202+ for analog wave filters.

Lattice:
This subclass is indented under subclass 300. Subject matter in which the filter has four computational or delay elements connected in series to form a closed circuit with two nonadjacent ports serving as the input terminals with the other two ports serving as output terminals.

SEE OR SEARCH CLASS:
333, Wave Transmission Lines and Networks, subclass 169 for analog lattice filters.

Transversal:
This subclass is indented under subclass 300. Subject matter in which feedforward processing of present inputs is utilized.

SEE OR SEARCH THIS CLASS, SUBCLASS:
425 for correlation using tapped delay line.

Recursive:
This subclass is indented under subclass 300. Subject matter in which the present filter output is a function of present inputs and past filter outputs.

Nontime domain:
This subclass is indented under subclass 300. Subject matter where the data when processed is not in the time domain.
(1) Note. Frequently this data is in the frequency domain.

Adaptive:
This subclass is indented under subclass 300. Subject matter where the transfer function of the filter is automatically changed as a function of the input signal.

Equalizer:
This subclass is indented under subclass 321. Subject matter where adaptive compensation for transmission medium noise imposition is performed.

SEE OR SEARCH CLASS:
375, Pulse or Digital Communications, subclasses 229+ for equalizers in a digital communications system.

Transform:
This subclass is indented under subclass 200. Subject matter wherein the digital calculation performs a transformation of a given representation of a data signal to another representation without loss of information by an orthogonal transformation.

SEE OR SEARCH CLASS:
704, Data Processing: Speech Signal Processing, Linguistics, Language Translation, and Audio Compression/Decompression, subclasses 200+ for speech signal processing.

Multidimensional:
This subclass is indented under subclass 400. Subject matter including a specific apparatus which is used for computing an n-dimensional transform of an input signal with n greater or equal to two.

Discrete Cosine Transform (i.e., DCT):
This subclass is indented under subclass 400. Subject matter wherein the transformation performed is a Discrete Cosine Transform.

Fourier:
This subclass is indented under subclass 400. Subject matter wherein the transformation performed is a mathematical operation which decomposes a time varying signal into its complex frequency components (amplitude and the phase or real and imaginary components).

SEE OR SEARCH CLASS:
382, Image Analysis, subclass 280 for a Fourier transform performed on image data.

Fast Fourier Transform (i.e., FFT):
This subclass is indented under subclass 403. Subject matter wherein the transformation performed is a Fast Fourier Transform.

SEE OR SEARCH THIS CLASS, SUBCLASS:
405 for Discrete Fourier Transform.

Discrete Fourier Transform (i.e., DFT):
This subclass is indented under subclass 403. Subject matter wherein the transformation performed is a Discrete Fourier Transform.

SEE OR SEARCH THIS CLASS, SUBCLASS:
404 for Fast Fourier Transform.

Pipeline:
This subclass is indented under subclass 403. Subject matter wherein the transformation is performed in a pipeline where the output of one task is input to another until a desired sequence of tasks has been carried out.

SEE OR SEARCH THIS CLASS, SUBCLASS:
233 for multifunctional operation performed in a particular pipeline.
508 for floating point performed in a particular pipeline.
521 for arithmetical pipeline operation in general.
631 for multiple digit binary multiplication performed in a particular pipeline.

Systolic:
This subclass is indented under subclass 403. Subject matter
wherein the transformation is performed by a specific apparatus having an array of computational elements where data is transferred synchronously between nearest neighbor elements.

SEE OR SEARCH THIS CLASS, SUBCLASS:
509 for a particular systolic array used in floating point.
522 for a particular systolic array used in an arithmetical operation.

SEE OR SEARCH CLASS:
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing ( e.g., Processors) subclass 19 for systolic array processor architecture.

Radix greater than two:
This subclass is indented under subclass 403. Subject matter wherein a specific apparatus is used for computing an n-radix Fourier Transform with n greater than two.

Butterfly circuit:
This subclass is indented under subclass 403. Subject matter wherein a specific apparatus performs a complex multiplication and a complex addition or subtraction.

Walsh:
This subclass is indented under subclass 400. Subject matter wherein the transformation performed is a Walsh Transform.

SEE OR SEARCH CLASS:
382, Image Analysis, subclass 281 for image transformation or processing using a Walsh Transform.

Convolution:
This subclass is indented under subclass 200. Subject matter which the convolution integral is evaluated in a digital fashion.
(1) Note. Frequently, the output of a system is determined by convolving the system input with the system impulse response.

SEE OR SEARCH THIS CLASS, SUBCLASS:
5 for hybrid computer convolution.
315 for convolution in digital filtering.
subclasses 813+ for analog computer convolution.

SEE OR SEARCH CLASS:
382, Image Analysis, subclass 279 for convolution in image preliminary processing or transformation.

Cyclic/circular:
This subclass is indented under subclass 420. Subject matter where the convolution integral of a and b, two series of discrete values, is found by performing a transform operation on a and b (producing A and B respectively) and then performing the inverse transform operation on the product of A and B.

Correlation:
This subclass is indented under subclass 200. Subject matter where the particular function determines the degree of correspondence between two series of discrete values by digitally evaluating the correlation integral.

SEE OR SEARCH THIS CLASS, SUBCLASS:
5 for hybrid computer correlation.
subclasses 813+ for analog computer correlation.

SEE OR SEARCH CLASS:
382, Image Analysis, subclass 278 for correlation in image preliminary processing or transformation.

Single bit data:
This subclass is indented under subclass 422. Subject matter in which the discrete values have a one bit representation.

Multidimensional data:
This subclass is indented under subclass 422. Subject matter in which at least one series of discrete values is multidimensional (e.g., image data).

SEE OR SEARCH THIS CLASS, SUBCLASS:
814 for analog correlation of multidimensional data.

SEE OR SEARCH CLASS:
382, Image Analysis, subclass 278 for correlation used in image transformation or prerecognition processing.

Using tapped delay line:
This subclass is indented under subclass 422. Subject matter where the outputs from successive stages of a digital delay element are utilized.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 301+ for related structure utilized in a filtering environment.
818 for analog correlation having a tapped delay line.

Autocorrelation:
This subclass is indented under subclass 422. Subject matter in which both series of discrete values are from a single source.

Evaluation of trigonometric function:
This subclass is indented under subclass 200. Subject matter wherein the particular function performed is the processing of a signal either to determine a trigonometric relationship or to operate on a signal in accordance with a trigonometric relationship.

SEE OR SEARCH THIS CLASS, SUBCLASS:
276 for waveform generation having trigonometric relationships.
811 for evaluation of trigonometric function by analog computer.

Vector resolver:
This subclass is indented under subclass 440. Subject matter wherein the signal is a vector and the operation is determining the vector components.

SEE OR SEARCH THIS CLASS, SUBCLASS:
809 for a vector resolver using analog computer.

Coordinate conversion:
This subclass is indented under subclass 200. Subject matter wherein the particular function performed is conversion of coordinates from one coordinate system to another (e.g., rectangular to polar).
(1) Note. The calculation of the change in coordinates resulting from a translation or rotation of a reference coordinate system is included in this subclass.

SEE OR SEARCH THIS CLASS, SUBCLASS:
809 for a coordinate conversion using analog computer.

Differentiation:
This subclass is indented under subclass 200. Subject matter for differentiation of at least one of a plurality of input signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:
6 for hybrid computer differentiation.
822 for analog differentiation.

Integration:
This subclass is indented under subclass 200. Subject matter for the integration of a sequence of discrete values of an input signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:
6 for hybrid computer integration.
subclasses 823+ for analog integration.

Averaging:
This subclass is indented under subclass 200. Subject matter for determining the average of a sequence of discrete values.

SEE OR SEARCH THIS CLASS, SUBCLASS:
805 for analog computer averaging.

SEE OR SEARCH CLASS:
702, Data Processing: Measuring, Calibrating, or Testing, subclass 194 for averaging in measured signal noise suppression.

Solving equation:
This subclass is indented under subclass 200. Subject matter wherein the specialized function performed is to solve an equation.
(1) Note. Excluded are arithmetical operations.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 490+ for digital arithmetical operations.

Arithmetical operation:
This subclass is indented under subclass 200. Subject matter wherein numerical quantities form the elements of the calculation, including the fundamental operations of arithmetic (addition, subtraction, multiplication, comparison, and division).

Residue number:
This subclass is indented under subclass 490. Subject matter wherein the numerical digits are in the residue number system.

SEE OR SEARCH THIS CLASS, SUBCLASS:
532 for residue code error detection or correction.

Galois field:
This subclass is indented under subclass 490. Subject matter where the arithmetical operations are performed on a 2 m element finite arithmetic field.

Multi-valued:
This subclass is indented under subclass 490. Subject matter where the arithmetical operations are performed with multi-valued operands.

Incremental mode:
This subclass is indented under subclass 490. Subject matter wherein the numerical digits represent a change in numbers as opposed to whole number representation.

SEE OR SEARCH CLASS:
375, Pulse or Digital Communications, subclasses 247+ for delta modulation.

Floating point:
This subclass is indented under subclass 490. Subject matter wherein the numerical digits are expressed in terms of a bounded number (mantissa) and a scale factor (characteristic or exponent) consisting of a power of the number base.

Compensation for finite word length:
This subclass is indented under subclass 495. Subject matter wherein the operation results in a word modification in length due to insufficient representation of using the fixed word length of the arithmetic system.

SEE OR SEARCH THIS CLASS, SUBCLASS:
306 for finite arithmetic effect in digital filtering.
subclasses 550+ for compensation for finite word length used in arithmetical operations.

Round off or truncation:
This subclass is indented under subclass 496. Subject matter wherein the modification is a deletion of one or more of the least significant digits and an adjustment of the more significant digits in accordance with some specific rule.

SEE OR SEARCH THIS CLASS, SUBCLASS:
551 for round off or truncation in arithmetical operations.

Overflow or underflow:
This subclass is indented under subclass 496. Subject matter wherein the modification is necessary because the word is either too large or too small to be represented using the fixed word length.

SEE OR SEARCH THIS CLASS, SUBCLASS:
552 for overflow or underflow used in arithmetical operations.

Sticky bit:
This subclass is indented under subclass 496. Subject matter wherein the modification is based on whether or not a number of least significant digits contains a one.

Evaluation of root:
This subclass is indented under subclass 495. Subject matter wherein the operation performed is the determination of a root.

SEE OR SEARCH THIS CLASS, SUBCLASS:
605 for evaluation of root by digital arithmetic operations.
807 for analog evaluation of root.

Multiplication followed by addition:
This subclass is indented under subclass 495. Subject matter wherein the operation performed is multiplication followed by an addition.

SEE OR SEARCH THIS CLASS, SUBCLASS:
523 for performing a multiplication followed by addition in arithmetic operations.

Reciprocal:
This subclass is indented under subclass 495. Subject matter wherein the operation performed is the determination of the reciprocal.

Multiplication:
This subclass is indented under subclass 495. Subject matter wherein the operation performed is multiplication.

SEE OR SEARCH THIS CLASS, SUBCLASS:
7 for hybrid computer multiplication.
subclasses 620+ for performing a multiplication in digital arithmetical operations.
subclasses 835+ for analog multiplication.

Division:
This subclass is indented under subclass 495. Subject matter wherein the operation performed is division.

SEE OR SEARCH THIS CLASS, SUBCLASS:
7 for hybrid computer division.
subclasses 650+ for division by digital computer.
844 for division by analog computer.

Addition or subtraction:
This subclass is indented under subclass 495. Subject matter wherein the operation performed is addition or subtraction.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 670+ for addition/subtraction by digital computer.

Feedback:
This subclass is indented under subclass 495. Subject matter wherein the operation is effected by the return of a portion of the output to its input.

SEE OR SEARCH THIS CLASS, SUBCLASS:
632 for feeding back partial product to complete the multiple digit binary multiplication.

Parallel:
This subclass is indented under subclass 495. Subject matter wherein the operation is effected by the use of two or more processors running simultaneously.

Pipeline:
This subclass is indented under subclass 495. Subject matter wherein the operation is effected by passing the output of one task as input to another until a desired sequence of tasks has been carried out.

SEE OR SEARCH THIS CLASS, SUBCLASS:
233 for multifunctional operation performed in a particular pipeline.
406 for Fourier transformation performed in a particular pipeline.
521 for arithmetical pipeline operation in general.
631 for multiple digit binary multiplication performed in a particular pipeline.

Systolic:
This subclass is indented under subclass 495. Subject matter wherein the operation is effected by a specific apparatus using an array of computational elements where data is transferred synchronously between nearest neighbor elements.

SEE OR SEARCH THIS CLASS, SUBCLASS:
407 for a particular systolic array used in a Fourier transform.
522 for a particular systolic array used in an arithmetical operation.

SEE OR SEARCH CLASS:
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing (e.g., Processors), subclass 19 for systolic array processor architecture.

Microprocessor:
This subclass is indented under subclass 495. Subject matter wherein the operation is effected by a microprocessor.

SEE OR SEARCH THIS CLASS, SUBCLASS:
231 for a particular microprocessor used in a multifunctional operation.
303 for a particular microprocessor used in filtering.

SEE OR SEARCH CLASS:
712, Electrical Computers and Digital Processing Systems:
Processing Architectures and Instruction Processing ( e.g., Processors) subclasses 32+ for particular microprocessor architecture.

Complex number format:
This subclass is indented under subclass 495. Subject matter wherein the numerical digits have a real part and an imaginary part.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 622+ for using complex number format in a multiplication operation.

Logarithmic format:
This subclass is indented under subclass 495. Subject matter wherein the numerical digits which constitute an operand represented by the exponent to which a base number must be raised to produce the operand.

SEE OR SEARCH THIS CLASS, SUBCLASS:
517 for logarithmic format in arithmetical operations.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 350+ for miscellaneous circuits providing a logarithmic function of an input signal.

Variable length or precision:
This subclass is indented under subclass 495. Subject matter wherein the numerical digits which constitute an operand are of selectable length or provide more detail.

SEE OR SEARCH THIS CLASS, SUBCLASS:
518 for variable length in digital arithmetical operations.

Matrix array:
This subclass is indented under subclass 495. Subject matter wherein the data is operated on by elements arranged in rows and columns.

SEE OR SEARCH THIS CLASS, SUBCLASS:
520 for a arithmetic matrix array operation in general.
607 for a particular multiplication of matrices.

SEE OR SEARCH CLASS:
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing (e.g., Processors) subclasses 2+ for vector processor architecture.

Logarithmic format:
This subclass is indented under subclass 490. Subject matter where an operand is represented by the exponent to which a base number must be raised to produce the operand.

SEE OR SEARCH THIS CLASS, SUBCLASS:
512 for logarithmic format in floating point.

Variable length:
This subclass is indented under subclass 490. Subject matter wherein the number of numerical digits that represent numbers are of differing length.

SEE OR SEARCH THIS CLASS, SUBCLASS:
513 for variable length or precision in floating point.

Negative radix:
This subclass is indented under subclass 490. Subject matter wherein the numerical digits are represented in negative radix format.

Matrix array:
This subclass is indented under subclass 490. Subject matter wherein the data is operated on by elements arranged in rows and columns.
(1) Note. Matrix array processing of multiplication or division per se is classified elsewhere.

SEE OR SEARCH THIS CLASS, SUBCLASS:
514 for a particular matrix array with floating point.
607 for multiplication of matrices.
subclasses 620+ for multiplication which may incorporate a matrix array.
subclasses 650+ for division which may incorporate a matrix array.

SEE OR SEARCH CLASS:
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing (e.g., Processors) subclasses 2+ for vector processor architecture.

Pipeline:
This subclass is indented under subclass 490. Subject matter wherein the operation is performed in a pipeline by passing the output of one task as input to another until a desired sequence of tasks has been carried out.
(1) Note. Pipeline processing of multiplication or division per se is classified elsewhere.

SEE OR SEARCH THIS CLASS, SUBCLASS:
233 for multifunctional operation performed in a particular
pipeline.
406 for Fourier transform performed in a particular pipeline.
508 for floating point performed in a particular pipeline.
subclasses 620+ for multiplication which may incorporate pipeline processing, particularly
631 for multiple digit binary multiplication performed in a particular pipeline.
subclasses 650+ for division which may incorporate pipeline processing.

Systolic:
This subclass is indented under subclass 490. Subject matter wherein the operation is effected by a specific apparatus using an array of computational elements where data is transferred synchronously between nearest neighbor elements.
(1) Note. Systolic processing of multiplication or division per se is classified elsewhere.

SEE OR SEARCH THIS CLASS, SUBCLASS:
407 for a particular systolic array used in a Fourier transform.
509 for a particular systolic array used in floating point.
subclasses 620+ for multiplication which may incorporate systolic processing.
subclasses 650+ for division which may incorporate systolic processing.

SEE OR SEARCH CLASS:
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing ( e.g., Processors) subclass 19 for systolic array processor architecture.

Multiplication followed by addition (i.e., x*y+z):
This subclass is indented under subclass 490. Subject matter wherein the operation performed is a multiplication followed by an addition.

SEE OR SEARCH THIS CLASS, SUBCLASS:
501 for performing a multiplication followed by addition with floating point.

Multiple parallel operations:
This subclass is indented under subclass 490. Subject matter including two or more operations in which numerical digits are transmitted simultaneously on separate lines.

Status condition/flag generation or use:
This subclass is indented under subclass 490. Subject matter where an indicator of the present data processing status is generated or used to select from a plurality of future processing paths.

SEE OR SEARCH THIS CLASS, SUBCLASS:
306 for flag generation or use in a digital filtering finite arithmetic effect environment.

Error detection or correction:
This subclass is indented under subclass 490. Subject matter with means identifying a malfunction in the operation of the apparatus or the result produced.

SEE OR SEARCH CLASS:
714, Error Detection/Correction and Fault Detection/Recovery, appropriate subclass for systems which test for malfunction in nonarithmetical operations.

Parity check:
This subclass is indented under subclass 530. Subject matter wherein the error detection or correction utilizes a parity bit.

SEE OR SEARCH CLASS:
340, Communications: Electrical, subclass 146.2 for detecting error in information content of a group of signals by parity check.
714, Error Detection/Correction and Fault Detection/Recovery, appropriate subclass for systems which test for malfunction in nonarithmetical operations.

Residue code:
This subclass is indented under subclass 530. Subject matter wherein the error detection or correction utilizes a residue code.
(1) Note. The residue is the remainder after dividing a number by a modulus n.

SEE OR SEARCH THIS CLASS, SUBCLASS:
491 for residue number arithmetical operation.

SEE OR SEARCH CLASS:
714, Error Detection/Correction and Fault Detection/Recovery, subclass 808 for error detection by residue code in nonarithmetic operations.

Sequential repetition:
This subclass is indented under subclass 530. Subject matter wherein the error detection or correction utilizes sequential repetition.

Plural parallel devices:
This subclass is indented under subclass 530. Subject matter wherein the error detection or correction utilizes plural parallel devices.

SEE OR SEARCH CLASS:
714, Error Detection/ Correction and Fault Detection/ Recovery subclasses 3+ for fault recovery including masking or reconfiguring, per se, in a digital data processing system and subclasses 820+ for plural parallel devices/channels in nonarithmetic operations.

Cathode-ray tube:
This subclass is indented under subclass 490. Subject matter wherein the specific apparatus for performing the arithmetic operation utilizes a cathode-ray tube.

SEE OR SEARCH CLASS:
315, Electric Lamp and Discharge Devices: Systems, subclasses 1+ for cathode ray tube circuits in general.

Contact-making device:
This subclass is indented under subclass 490. Subject matter wherein the specific apparatus for performing the arithmetic operation utilizes a contact-making device such as a relay.

SEE OR SEARCH CLASS:
200, Electricity: Circuit Makers and Breakers, appropriate subclasses for electrical switches, per se.

Radix point control:
This subclass is indented under subclass 490. Subject matter for controlling the radix point position relative to the numerical digits, e.g., controlling the position of a decimal point.

SEE OR SEARCH THIS CLASS, SUBCLASS:
498 for overflow or underflow used in floating point.

Compensation for finite word length:
This subclass is indented under subclass 490. Subject matter wherein the operation results in a word modification in length due to insufficient representation of using the fixed word length of the arithmetic system.

SEE OR SEARCH THIS CLASS, SUBCLASS:
306 for finite arithmetic effect in digital filtering.
subclasses 496+ for a particular compensation for finite word length used in a floating point.

Round off or truncation:
This subclass is indented under subclass 550. Subject matter wherein the modification is an adjustment of the more significant digits in accordance with some specific rule or a deletion of one or more of the least significant digits.

SEE OR SEARCH THIS CLASS, SUBCLASS:
497 for round off or truncation used in floating point.

Overflow or underflow:
This subclass is indented under subclass 550. Subject matter wherein the modification is necessary because the word is either too large or too small to be represented using the fixed word length.

SEE OR SEARCH THIS CLASS, SUBCLASS:
498 for overflow or underflow in floating point processing.

Prediction:
This subclass is indented under subclass 552. Subject matter wherein the overflow or underflow is forecasted before the operation is performed.

Sum of products generation:
This subclass is indented under subclass 490. Subject matter for producing and adding together a plurality of operand product terms.

SEE OR SEARCH THIS CLASS, SUBCLASS:
319 for similar processing in a transversal filter environment.
420 for similar processing in digital convolution.

All four basic functions:
This subclass is indented under subclass 490. Subject matter wherein the computer has the capability of performing the functions of multiplication, division, addition and subtraction.

Evaluation of root:
This subclass is indented under subclass 490. Subject matter wherein the arithmetic operation performed is the determination of roots.

SEE OR SEARCH THIS CLASS, SUBCLASS:
807 for evaluation of root by analog computer.

Evaluation of powers:
This subclass is indented under subclass 490. Subject matter wherein the arithmetic operation performed is the raising of numbers to powers.

SEE OR SEARCH THIS CLASS, SUBCLASS:
808 for evaluation of powers by analog computer.

Multiplication of matrices:
This subclass is indented under subclass 490. Subject matter wherein multiplication is performed on plural sets of data arranged in rows and columns.

SEE OR SEARCH THIS CLASS, SUBCLASS:
514 for a particular floating point matrix array.
520 for a particular arithmetic operation matrix array.

SEE OR SEARCH CLASS:
712, Electrical Computers and Digital Processing Systems: Processing Architectures and Instruction Processing (e.g., Processors) subclasses 2+ for vector processor architecture.

Multiplication:
This subclass is indented under subclass 490. Subject matter wherein the arithmetic operation performed is multiplication.

SEE OR SEARCH THIS CLASS, SUBCLASS:
7 for multiplication by hybrid computer.
503 for performing multiplication in floating point.
835 for multiplication by analog computer.

Complex number format:
This subclass is indented under subclass 620. Subject matter wherein the numerical digits have a real part and an imaginary part.

SEE OR SEARCH THIS CLASS, SUBCLASS:
511 for using complex number format in floating point.

Decimal:
This subclass is indented under subclass 620. Subject matter wherein the numerical digits are of radix ten.

SEE OR SEARCH THIS CLASS, SUBCLASS:
624 for coded decimal multiplication.

Coded decimal:
This subclass is indented under subclass 620. Subject matter wherein the numerical digits are of radix ten expressed in terms of another lesser radix.

SEE OR SEARCH THIS CLASS, SUBCLASS:
623 for decimal multiplication.

Binary:
This subclass is indented under subclass 620. Subject matter wherein the numerical digits are of radix two.

SEE OR SEARCH THIS CLASS, SUBCLASS:
624 for arithmetic operations on digits of radix two within a denomination.
654 for division by multiplication by reciprocal.

Sum of cross products:
This subclass is indented under subclass 625. Subject matter wherein the multiplication is effected by the sum of cross products technique.

Repeated addition:
This subclass is indented under subclass 625. Subject matter wherein the multiplication is effected by the repeated addition technique.

Multiple digit:
This subclass is indented under subclass 627. Subject matter wherein at a given instant of time a plurality of multiplier digits control the repeated addition operation.

Carry-save adders (i.e., CSAs):
This subclass is indented under subclass 628. Subject matter including an array of carry-save adders to perform the multiplication.

SEE OR SEARCH THIS CLASS, SUBCLASS:
708 for parallel carry-save adders in binary addition/subtraction.

Array adders:
This subclass is indented under subclass 628. Subject matter including an array of circuits or integrated circuits that sum the amplitude of two input signals to perform the multiplication.

Pipeline:
This subclass is indented under subclass 628. Subject matter including a specific apparatus passing the output of one task as input to another until a desired sequence of tasks has been carried out.

SEE OR SEARCH THIS CLASS, SUBCLASS:
233 for multifunctional operation performed in a particular pipeline.
406 for Fourier transformation performed in a particular pipeline.
508 for floating point performed in a particular pipeline.
521 for arithmetical pipeline operation in general.

Feedback:
This subclass is indented under subclass 628. Subject matter including means which involves feeding back a partial product as an input to complete the multiplication.

SEE OR SEARCH THIS CLASS, SUBCLASS:
506 for feeding back a portion of the output to its input in floating point.

Division:
This subclass is indented under subclass 490. Subject matter wherein the arithmetic operation performed is division.

SEE OR SEARCH THIS CLASS, SUBCLASS:
7 for division by hybrid computer.
504 for floating point division.
844 for division by analog computer.

Decimal:
This subclass is indented under subclass 650. Subject matter wherein the numerical digits are of radix ten.

SEE OR SEARCH THIS CLASS, SUBCLASS:
623 for decimal multiplication.
652 for coded decimal division.

Coded decimal:
This subclass is indented under subclass 650. Subject matter wherein the numerical digits are of radix ten expressed in terms of another lesser radix.

SEE OR SEARCH THIS CLASS, SUBCLASS:
624 for coded decimal multiplication.
651 for decimal division.

Binary:
This subclass is indented under subclass 650. Subject matter wherein the numerical digits are of radix two.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 625+ for binary multiplication.

Multiplication by reciprocal:
This subclass is indented under subclass 653. Subject matter wherein the division is effected by multiplying the dividend by the reciprocal of the divisor.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 625+ for binary multiplication in general.

Repeated subtraction:
This subclass is indented under subclass 653. Subject matter wherein the division is effected by the repeated subtraction technique.

Multiples of divisor:
This subclass is indented under subclass 655. Subject matter wherein multiples of the divisor are used in the repeated subtraction operation.

Addition/subtraction:
This subclass is indented under subclass 490. Subject matter wherein the arithmetic operation performed is addition or subtraction.

SEE OR SEARCH THIS CLASS, SUBCLASS:
505 for floating point addition or subtraction.

SEE OR SEARCH CLASS:
326, Electronic Digital Logic Circuitry, subclass 53 for an electronic digital logic type quarter or half-adder.
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 355+ for miscellaneous adding or subtracting circuits.

Comparison:
This subclass is indented under subclass 670. Subject matter for comparing by determining the mathematical magnitude of the difference between two numbers.

SEE OR SEARCH THIS CLASS, SUBCLASS:
207 for determination of maximum of" or minimum of" a series of numbers by comparison.

SEE OR SEARCH CLASS:
340, Communications: Electrical, subclass 146.2 for digital comparator system.

Incrementation/decrementation:
This subclass is indented under subclass 670. Subject matter for incrementation or decrementation which is performed by changing by one the value of the numerical digit in the least significant digit position.

SEE OR SEARCH CLASS:
377, Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, for electrical pulse counters and counting systems.

Radix correction:
This subclass is indented under subclass 670. Subject matter for correction for a change in radix.
(1) Note. For example, binary coded decimal with 6" correction.

SEE OR SEARCH THIS CLASS, SUBCLASS:
683 for a device operating in coded decimal fashion that does not require radix correction.

Serial:
This subclass is indented under subclass 673. Subject matter wherein the radix correction is performed by operation on the numerical digits in a serial manner.

Signal amplitude:
This subclass is indented under subclass 670. Subject matter wherein the addition or subtraction is performed by summing signal amplitudes.

Microwave:
This subclass is indented under subclass 670. Subject matter wherein the addition or subtraction is performed utilizing a microwave device.

Cryogenic:
This subclass is indented under subclass 670. Subject matter wherein the addition or subtraction is performed utilizing a cryogenic device.

SEE OR SEARCH CLASS:
505, Superconductor Technology: Apparatus, Material, Process, appropriate subclasses for superconductor technology.

By electronic tube:
This subclass is indented under subclass 670. Subject matter wherein the addition or subtraction is performed utilizing an electronic tube.

Magnetic:
This subclass is indented under subclass 670. Subject matter wherein the addition or subtraction is performed utilizing a magnetic device.

Decimal:
This subclass is indented under subclass 670. Subject matter wherein the numerical digits are of radix ten.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 683+ for coded decimal addition/subtraction.

Serial:
This subclass is indented under subclass 680. Subject matter wherein the numerical digits are operated on in a serial manner.

Parallel:
This subclass is indented under subclass 680. Subject matter wherein the numerical digits are operated on in a parallel manner.

Coded decimal:
This subclass is indented under subclass 670. Subject matter wherein the numerical digits are of radix ten expressed in terms of another lesser radix.

SEE OR SEARCH THIS CLASS, SUBCLASS:
673 for a device which accomplishes radix correction.
680 for decimal addition/subtraction.

Serial:
This subclass is indented under subclass 683. Subject matter wherein the numerical digits are operated on in a serial manner.

Parallel:
This subclass is indented under subclass 683. Subject matter wherein the numerical digits are operated on in a parallel manner.

Binary:
This subclass is indented under subclass 670. Subject matter wherein the numerical digits are of radix two.

Bipolar junction transistor only or combined with Field-Effect Transistor:
This subclass is indented under subclass 700. Subject matter including a transistor that uses both negative and positive charge carriers or combined with a transistor in which current carriers (holes or electrons) are injected at one terminal (the source) and pass to another (the drain) through a channel of semiconductor material whose resistivity depends mainly on the extent to which it is penetrated by a depletion region.

Field-Effect Transistor (FET):
This subclass is indented under subclass 700. Subject matter including a transistor in which current carriers (holes or electrons) are injected at one terminal (the source) and pass to another (the drain) through a channel of semiconductor material whose resistivity depends mainly on the extent to which it is penetrated by a depletion region.

Gate function level:
This subclass is indented under subclass 700. Subject matter including means to show a gate functional level or combined with a transistor.

For precharging (e.g., Manchester, etc.):
This subclass is indented under subclass 700. Subject matter using clock signal for precharging a field-effect transistor.

Serial:
This subclass is indented under subclass 700. Subject matter wherein the numerical digits are operated on in a serial manner.

Parallel:
This subclass is indented under subclass 700. Subject matter wherein the numerical digits are operated upon in a simultaneous manner.

SEE OR SEARCH THIS CLASS, SUBCLASS:
507 for providing the digits in a parallel manner in floating point.

Carry-ripple:
This subclass is indented under subclass 706. Subject matter wherein a carry signal ripples through each digit.

SEE OR SEARCH THIS CLASS, SUBCLASS:
711 for block of carry-out signal.

Carry-save adders:
This subclass is indented under subclass 706. Subject matter including more than one carry-save adder for performing the addition.

SEE OR SEARCH THIS CLASS, SUBCLASS:
629 for carry-save adders in binary multiplication.

Adding more than two numbers:
This subclass is indented under subclass 706. Subject matter wherein at least three numbers are added.

Carry look-ahead:
This subclass is indented under subclass 706. Subject matter wherein the addition or subtraction is performed by a circuit which predicts the final carry from propagate and generate signals supplied by partial adders.

SEE OR SEARCH THIS CLASS, SUBCLASS:
712 for the carry-out signals of the blocks.

Slice block having block ripple:
This subclass is indented under subclass 710. Subject matter wherein carry-out signal of a block ripples through the next block.

SEE OR SEARCH THIS CLASS, SUBCLASS:
707 for the carry signal ripple through each digit.

Slice block having block look-ahead:
This subclass is indented under subclass 710. Subject matter wherein the carry signals of the blocks look-ahead.

Tree structured logic blocks:
This subclass is indented under subclass 710. Subject matter including more than one logic block containing one or more nodes that are linked together in a hierarchical fashion.

Conditional sums:
This subclass is indented under subclass 706. Subject matter wherein the addition or subtraction is performed utilizing
conditional sums.

ELECTRICAL ANALOG CALCULATING COMPUTER:
This subclass is indented under the class definition. Subject matter which includes devices for performing calculation operations upon electrical signals, such as current or voltage, which are continuously varying representations of physical quantities and which are some function of the quantities such as direct proportion, inverse proportion or square law relationship.
(1) Note. The limited logic operations include comparison or selection, for example.
(2) Note. The continuously varying representations, for example, may be frequency or pulse width.
(3) Note. Signals wherein the varying representation is pulse rate are included with subject matter under Electric Digital Calculating Computer".
(4) Note. Examples of the physical quantities above are temperature, pressure, angular position, or weight numerical values.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 1+ for electrical hybrid calculating computers.
subclasses 100+ for electrical digital calculating computers.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, appropriate subclasses for miscellaneous active device analog circuits.

Particular function performed:
This subclass is indented under subclass 800. Subject matter directed to a particular function performed by an analog computer or subcombination thereof in making a computation.
(1) Note. For classification herein the function performed must be significantly claimed in making a computation.

SEE OR SEARCH CLASS:
706, Data Processing: Artificial Intelligence, subclasses 1+ for fuzzy logic hardware and subclasses 15+ for neural networks.

Evaluation of equation:
This subclass is indented under subclass 801. Subject matter for obtaining the solution to a mathematical problem.
(1) Note. The mathematical problem may be expressed as equations, conditions, etc., and the solution may be a value or set of values or the value which meets some objective criteria.
(2) Note. This subclass includes subject matter which utilized an analog signal as a computing component and in which the computing component is employed more than once to determine a mathematical solution by successive steps.
(3) Note. This subclass does not include subject matter classifiable as specific types of problems or operations found below.

Simultaneous:
This subclass is indented under subclass 802. Subject matter for the solution of simultaneous equations or conditions.
(1) Note. Linear programming problems are included herein.

SEE OR SEARCH CLASS:
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, subclasses 7+ for operations research processing.

Differential (e.g., differential analyzer):
This subclass is indented under subclass 802. Subject matter wherein the equations evaluated are differential equations.

SEE OR SEARCH THIS CLASS, SUBCLASS:
102 for differential analyzers of the digital type.

Averaging:
This subclass is indented under subclass 801. Subject matter wherein the function performed is determining an average amplitude for a signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:
445 for averaging by means of a digital calculating computer.

SEE OR SEARCH CLASS:
702, Data Processing: Measuring, Calibrating, or Testing, subclass 194 for measured signal noise suppression by averaging.

Variance or standard deviation determination:
This subclass is indented under subclass 801. Subject matter wherein the function performed is determining variance or standard deviation.

SEE OR SEARCH CLASS:
702, Data Processing: Measuring, Calibrating, or Testing, subclasses 179+ for statistical measurement.

Evaluation of root (e.g., square root):
This subclass is indented under subclass 801. Subject matter wherein the function performed is root evaluation.

SEE OR SEARCH THIS CLASS, SUBCLASS:
605 for evaluation of root by digital computer.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices,
Circuits, and Systems, subclasses 346+ for miscellaneous circuits in which an output signal is exponentially related to an input signal.

Evaluation of powers:
This subclass is indented under subclass 801. Subject matter wherein the function performed is the evaluation of the powers of an input signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:
606 for evaluation of powers by digital computer.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 346+ for miscellaneous circuits in which an output signal is exponentially related to an input signal.

Coordinate conversion or vector resolver:
This subclass is indented under subclass 801. Subject matter wherein the computer converts from one coordinate system to another, such as from rectangular to polar or resolving a vector into its coordinate values.

SEE OR SEARCH THIS CLASS, SUBCLASS:
441 for a vector resolver using digital computer.
442 for a coordinate conversion using digital computer.

SEE OR SEARCH CLASS:
235, Registers, subclass 61 for coordinate conversion by mechanical computers and subclass 410 for coordinate conversion in ordnance computers.
318, Electricity: Motive Power Systems, subclass 605 for synchros or resolvers used in analog comparison techniques for digital or numerical positional servo systems and subclass 661 for resolver type differential transformer systems used as a particular position measuring instrument for a positional servo error detecting means.

Electromechanical:
This subclass is indented under subclass 809. Subject matter wherein the function is performed utilizing an electromechanical device.

Evaluation of trigonometric function:
This subclass is indented under subclass 801. Subject matter wherein the function performed is processing of a signal to either determine a trigonometric relationship or to operate on a signal in accordance with a trigonometric relationship.
(1) Note. Generation of a waveform having trigonometric relationship(s) is included herein.

SEE OR SEARCH THIS CLASS, SUBCLASS:
440 for evaluation of trigonometric function by digital computer.

Single triangle:
This subclass is indented under subclass 811. Subject matter which solves for an unknown parameter of a plane triangle.

Correlation or convolution:
This subclass is indented under subclass 801. Subject matter for evaluating cross-correlation, auto-correlation, cross-convolution or auto-convolution functions.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 420+ for convolution by digital computer.
subclasses 422+ for correlation by digital computer.

SEE OR SEARCH CLASS:
324, Electricity: Measuring and Testing, subclass 76.12 and indented subclass for correlators used in frequency spectrum analyzer systems.
342, Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation), subclasses 378+ for directive radio wave communications systems using correlation techniques.
367, Communications, Electrical: Acoustic Wave Systems and Devices, subclasses 38+ for correlators used in geophysical communications systems.

Of multidimensional data:
This subclass is indented under subclass 813. Subject matter wherein the correlation or convolution is of multidimensional data.

SEE OR SEARCH THIS CLASS, SUBCLASS:
424 for digital correlation of multidimensional data.

SEE OR SEARCH CLASS:
342, Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation), subclass 5 for correlation functions employed in radar systems with map matching.

Acoustic:
This subclass is indented under subclass 813. Subject matter utilizing compressional wave propagation along or through a medium other than a light modulator.

SEE OR SEARCH THIS CLASS, SUBCLASS:
816 for light modulation using compressional waves.

Optical:
This subclass is indented under subclass 813. Subject matter utilizing optical devices and producing an electrical output.

SEE OR SEARCH CLASS:
706, Data Processing: Artificial Intelligence, subclass 40 for optical neural networks.

Magnetic or electromagnetic:
This subclass is indented under subclass 813. Subject matter utilizing a magnetic or electromagnetic device.

Having tapped delay line:
This subclass is indented under subclass 813. Subject matter utilizing a tapped delay line.

SEE OR SEARCH THIS CLASS, SUBCLASS:
301 for related structure in digital filtering.
425 for correlation using tapped delay line.

Filtering:
This subclass is indented under subclass 801. Subject matter utilized for filtering electrical signals by computation.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 300+ for digital filtering.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 552+ for miscellaneous unwanted signal suppression utilizing an active filter circuit not performing an arithmetic calculation.
333, Wave Transmission Lines and Networks, subclass 18 for filters used in automatically controlled equalizer or delay networks; subclass 28 for analog filters in equalizer coupling networks and subclasses 167+ for analog type transversal filter coupling networks.
375, Pulse or Digital Communications, subclasses 229+ and 285 for filtering techniques used in distortion or noise prevention or correction means for modulated carrier wave communication systems.
455, Telecommunications, subclass 307 for filtering in a radio receiver.
702, Data Processing: Measuring and Testing, subclasses 191+ for measured signal noise suppression.

Transform:
This subclass is indented under subclass 801. Subject matter wherein the function performed is transforming a given representation of a data signal to another representation without loss of information by an orthogonal transformation.

SEE OR SEARCH THIS CLASS, SUBCLASS:
5 for transform by hybrid computer.
subclasses 400+ for transform by digital calculating computer.

Fourier:
This subclass is indented under subclass 820. Subject matter wherein the transformation is from the time or space domain to the frequency domain or the converse.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 403+ for Fourier transform by digital calculating computer.

Differentiation:
This subclass is indented under subclass 801. Subject matter wherein the function performed is differentiation of at least
one of a plurality of input signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:
443 for differentiation by a digital computer.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclass 335 for a miscellaneous circuit providing the derivative of an input signal without computation.

Integrator:
This subclass is indented under subclass 801. Subject matter wherein the function performed is integration of at least one of a plurality of input signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:
444 for integration by a digital computer.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 336+ for a miscellaneous circuit providing the integral of an input signal without computation.

Plural integration:
This subclass is indented under subclass 823. Subject matter wherein the function performed is plural integration.

Plural mode (e.g., plural scale):
This subclass is indented under subclass 823. Subject matter wherein the apparatus is capable of operating in plural modes or scales.

Reset:
This subclass is indented under subclass 823. Subject matter wherein the integration operation is reset when the output meets a predetermined condition.

Drift correction:
This subclass is indented under subclass 823. Subject matter additionally including the function of drift correction.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclass 307 for miscellaneous baseline or DC offset correction circuits.

Having simultaneous calculation of another function:
This subclass is indented under subclass 823. Subject matter where the input signal on which integration is performed is simultaneously subject to a calculation function other than integration and the output is a function of both.

Having a voltage to frequency converter:
This subclass is indented under subclass 823. Subject matter utilizing a voltage to frequency converter.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclass 101 for conversion per se of input current or voltage to output frequency.

Electromechanical:
This subclass is indented under subclass 823. Subject matter utilizing an electromechanical device.

Electro-optical:
This subclass is indented under subclass 823. Subject matter utilizing an electro-optical device.

Magnetic or electromagnetic:
This subclass is indented under subclass 823. Subject matter utilizing a magnetic or electromagnetic device.

Amplifier with additional feedback loop:
This subclass is indented under subclass 823. Subject matter utilizing an integrating amplifier with an additional feedback loop.

SEE OR SEARCH CLASS:
330, Amplifiers, subclasses 75+ for amplifier circuits with signal feedback.

Additional R/C feedback loop:
This subclass is indented under subclass 833. Subject matter including a resistance or capacitance in the additional feedback loop.

Multiplication:
This subclass is indented under subclass 801. Subject matter wherein the function performed is multiplication.

SEE OR SEARCH THIS CLASS, SUBCLASS:
7 for hybrid computer multiplication.
subclasses 620+ for digital multiplication in general.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 356+ for a miscellaneous circuit providing the product of a plurality of inputs.

Time division:
This subclass is indented under subclass 835. Subject matter wherein one input variable is used to control the mark-to-space ratio and the other variable is used to control the amplitude of a repetitive rectangular wave.
(1) Note. Each variable can be represented by current or voltage and the output voltage, proportional to the area of the pulse voltage-time curve, represents the product of the input variables.

Quarter-square:
This subclass is indented under subclass 835. Subject matter wherein the product produced pertains to an analog multiplier whose operation is based upon the identity xy = (1/4) (x+y) 2 - (1/4) (x-y) 2.

Having charging or discharging of energy storage device:
This subclass is indented under subclass 835. Subject matter wherein the multiplication function is performed by charging or discharging of an energy storage device.

SEE OR SEARCH CLASS:
320, Electricity: Battery or Capacitor Charging or Discharging, subclass 1 or 2+ for a capacitor or battery charging or discharging circuit.
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, appropriate subclasses for miscellaneous circuits utilizing the charging or discharging of an energy storage device.

Photomultiplier:
This subclass is indented under subclass 835. Subject matter wherein the multiplication function is performed utilizing photomultipliers.

SEE OR SEARCH CLASS:
250, Radiant Energy, subclasses 206+ for photocell controlled circuits in general.

Electromagnetic:
This subclass is indented under subclass 835. Subject matter wherein the multiplication function is performed utilizing an electromagnetic device.

Hall effect:
This subclass is indented under subclass 840. Subject matter utilizing the Hall effect principle.

SEE OR SEARCH CLASS:
323, Electricity: Power Supply or Regulation Systems, subclass 294 and 368 for resistor-type impedance systems which operate under Hall effect principles.
324, Electricity: Measuring and Testing, subclass 207.2 for magnetic measuring using the Hall effect.
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclass 511 for miscellaneous Hall effect circuits.

Electromechanical (e.g., servo-multiplier):
This subclass is indented under subclass 835. Subject matter wherein the multiplication function is performed utilizing an electromechanical device.

Having alternative division:
This subclass is indented under subclass 835. Subject matter wherein the function performed is multiplication of two or more inputs and wherein a division is performed as an alternative function.

Division:
This subclass is indented under subclass 801. Subject matter wherein the function performed is division.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 650+ for division by digital computer in general.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclass 360 for miscellaneous circuits where the output is a quotient of a plurality of inputs.

Function generation:
This subclass is indented under subclass 801. Subject matter wherein the wave shape of at least one analog signal representing a desired function is generated by mathematical operation or a signal is generated as a part of a mathematical operation representing a desired function of at least one variable input parameter.
(1) Note. This and the indented subclasses include waveform synthesizers of the analog type wherein the waveform is internally generated.
(2) Note. Trigonometric waveform generation is excluded.

SEE OR SEARCH THIS CLASS, SUBCLASS:
subclasses 8+ and 270+, for electrical hybrid or electrical
digital computers which perform the function of function generation.
811 for evaluation or generation of trigonometric functions.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 100+ for miscellaneous signal converting, shaping, or generating circuits and subclasses 334+ for miscellaneous circuits providing a function of one or more input signals.

Piece-wise linear synthesis:
This subclass is indented under subclass 845. Subject matter wherein the desired function is approximated by a series of segments of straight lines.

SEE OR SEARCH THIS CLASS, SUBCLASS:
9 for a hybrid computer performing piece-wise linear synthesis.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 334+ for a miscellaneous circuit providing a piece-wise approximation to a desired input to output function.

Interpolation/extrapolation:
This subclass is indented under subclass 846. Subject matter including determining or estimating a value or values between two or more known predetermined points or by continuing the trend established between two or more known points.

SEE OR SEARCH THIS CLASS, SUBCLASS:
290 for interpolation/extrapolation by digital computer.

Diode breakpoint:
This subclass is indented under subclass 846. Subject matter wherein the function is performed by a network or networks of resistors and diodes in which the diodes begin to conduct at different values (breakpoints) of an input signal.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 583+ for miscellaneous diode circuits.

Cathode-ray tube:
This subclass is indented under subclass 845. Subject matter wherein sensing a pattern within or external to the envelope of a cathode-ray tube produces a function signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:
540 for a cathode ray tube used in digital arithmetical operation.

SEE OR SEARCH CLASS:
340, Communications: Electrical, subclass 324 for multiple variation cathode ray display electrical communication systems.

Two or more variables:
This subclass is indented under subclass 845. Subject matter wherein the signal represents two or more variables.

Logarithmic/exponential:
This subclass is indented under subclass 845. Subject matter wherein the particular generated function is logarithmic/exponential.

SEE OR SEARCH THIS CLASS, SUBCLASS:
277 for logarithmic/exponential function generation by digital computer.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 350+ for miscellaneous circuits providing a logarithmic function of an input signal.

Triangular, sawtooth, or ramp:
This subclass is indented under subclass 845. Subject matter wherein the particular generated function is of the triangular, sawtooth or ramp type.

SEE OR SEARCH THIS CLASS, SUBCLASS:
274 for a linear function generator by digital computer.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems, subclasses 131+ for miscellaneous circuits providing a sawtooth or ramp type waveform.

Hyperbolic:
This subclass is indented under subclass 845. Subject matter wherein the particular generated function is hyperbolic.

Electromechanical:
This subclass is indented under subclass 845. Subject matter wherein the function is performed utilizing an electromechanical device.