In navigation, dead reckoning (also ded [for deduced] reckoning or DR) is the process of calculating one's current position by using previously determined position, or fix, and advancing that position based upon known or estimated speeds over elapsed time and course.

As each estimate of position is relative to the previous one, errors are cumulative1, or compounding multiplicatively or exponentially, if that is the co-relationship of the quanta.

1 "signal" refers to the wanted information; "noise" is something unintentionally added to the signal: "These unwanted additions may be distortions of sound (in telephony, for example) or static (in radio), or distortions in shape or shading of picture (television), or errors in transmission (telegraphy for facsilimile), etc." Both signal and noise are information. What determines which is which?