ilogbl

SYNOPSIS
       #include <math.h>

       int ilogb(double x);
       int ilogbf(float x);
       int ilogbl(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       ilogb(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
       _ISOC99_SOURCE; or cc -std=c99
       ilogbf(), ilogbl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600
       || _ISOC99_SOURCE; or cc -std=c99

DESCRIPTION
       These  functions return the exponent part of their argument as a signed
       integer.  When no error occurs, these functions are equivalent  to  the
       corresponding logb(3) functions, cast to int.

RETURN VALUE
       On success, these functions return the exponent of x, as a signed inte-
       ger.

       If x is zero, then a domain error  occurs,  and  the  functions  return
       FP_ILOGB0.

       If  x  is  a  NaN, then a domain error occurs, and the functions return
       FP_ILOGBNAN.

       If x is negative infinity or positive infinity,  then  a  domain  error
       occurs, and the functions return INT_MAX.

ERRORS
       See  math_error(7) for information on how to determine whether an error
       has occurred when calling these functions.

       The following errors can occur:

       Domain error: x is 0 or a NaN
              An invalid floating-point exception (FE_INVALID) is raised.

              These functions do not set errno for this case.

       Domain error: x is an infinity

              These functions do not set errno or raise an exception for  this
              case.

CONFORMING TO
       C99, POSIX.1-2001.