Compute the integral part of a logarithm
#include <math.h> int ilogb ( double x ); int ilogbf (float x ); int ilogbl ( long double x );
The ilogb() and ilogbf() functions compute the integral part of:
log_{r} |x|
as a signed integral value, for nonzero finite x, where r is the radix of the machine's floating point arithmetic.
The exponent part of x, in integer format:
If x is: | These functions return: |
---|---|
0 | FP_ILOGB0 |
NAN | FP_ILOGBNAN |
±Inf | INT_MAX |
Safety: | |
---|---|
Cancellation point | No |
Interrupt handler | No |
Signal handler | No |
Thread | Yes |