a computer unit including a program, stored on computer-readable media, the program being adapted to determine a position of a calibrating body in an unpivoted starting position, determine a theoretical position that the calibrating body should occupy without pivoting error after a pivoting movement based on the unpivoted starting position, calculate a pivoting error correction value using a deviation value between a measured position of the calibrating body in the pivoted position and the theoretical position that the calibrating body should occupy in the pivoted position without a pivoting error, and to use the correction value, which compensates for the pivoting error in the pivoted position, to calculate one of a measuring point coordinate on a measurement object or a theoretical measuring-point coordinate to be approached on the measurement object when the measurement object is measured in a corresponding pivoted position.