The significand() function, along with the logb(3M) and scalb(3M) functions, allows users to verify compliance to ANSI/IEEE Std 754-1985 by running certain test vectors distributed by the University of California.

If x equals sig * 2ⁿ with 1 < sig < 2, then significand(x) returns sig for exercising the fraction-part(F) test vector. significand(x) is not defined when x is either 0, +-Inf or NaN.

For exceptional cases, matherr(3M) tabulates the values to be returned as dictated by various Standards.

See attributes(5) for descriptions of the following attributes:

logb(3M), matherr(3M), scalb(3M), attributes(5)