Index error

With measuring devices

Under index error is understood as the (usually inevitable) small mistake by which the reading on the scale of measuring instruments must be corrected.

It is caused by manufacturing-related or otherwise caused deviations of the "index line" (or the "pointer" on the measuring scale) from the ideal position. On many instruments, it can be eliminated or reduced through adjustment , but often only through its determination and subsequent attachment to the measured value .

The term is most commonly used with the sextant , but it also occurs as an altitude index error on the vertical circle of every theodolite and astronomical instrument. With accelerometers (accelerometers) in the inertial navigation , an index error means the incorrect display of a small acceleration, even if the speed is constant. It is corrected using special analysis methods in digital error models .

In the IT

In IT , the incorrect programming of the start or end values ​​of program loops or the indexing of a matrix , an array , etc. is called an index error .