cc [ flag ... ] file ... -lm [ library ... ] #include <math.h>double logb(double x);
The logb() function computes the exponent of x, which is the integral part of logr | x |, as a signed floating point value, for non-zero x, where r is the radix of the machine's floating-point arithmetic.
Upon successful completion, logb() returns the exponent of x.
If x is 0.0, logb() returns -HUGE_VAL and sets errno to EDOM.
If x is ±Inf, logb() returns +Inf.
If x is NaN, logb() returns 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:
|ATTRIBUTE TYPE||ATTRIBUTE VALUE|