ilogbl

       #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 ||
           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
           _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99
       ilogbf(), ilogbl():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
           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, and
              errno is set to EDOM (but see BUGS).

       Domain error: x is an infinity
              An invalid floating-point exception (FE_INVALID) is raised,  and
              errno is set to EDOM (but see BUGS).

ATTRIBUTES
       For   an   explanation   of   the  terms  used  in  this  section,  see
       tation of these functions:

       *  The  domain  error case where x is 0 or a NaN did not cause errno to
          be set or (on some architectures) raise a floating-point exception.

       *  The domain error case where x is an infinity did not cause errno  to
          be set or raise a floating-point exception.

SEE ALSO
       log(3), logb(3), significand(3)

COLOPHON
       This  page  is  part of release 4.04 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       http://www.kernel.org/doc/man-pages/.

                                  2015-04-19                          ILOGB(3)
Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2019 Hurricane Electric. All Rights Reserved.