ILOGB(3) Linux Programmer's Manual ILOGB(3)
NAME
ilogb, ilogbf, ilogbl  get integer exponent of a floating point value
SYNOPSIS
#include <<math.h>>
int ilogb(double x);
int ilogbf(float x);
int ilogbl(long double x);
Link with lm.
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). An error will occur
for zero and infinity and NaN, and possibly for overflow.
ERRORS
In order to check for errors, set errno to zero and call feclearex
cept(FE_ALL_EXCEPT) before calling these functions. On return, if
errno is nonzero or fetestexcept(FE_INVALID  FE_DIVBYZERO  FE_OVER
FLOW  FE_UNDERFLOW) is nonzero, an error has occurred.
If an error occurs and (math_errhandling & MATH_ERRNO) is nonzero,
then errno is set to EDOM. If an error occurs and (math_errhandling &
MATH_ERREXCEPT) is nonzero, then the invalid floatingpoint exception
is raised.
A domain error occurs when x is zero or infinite (or too large, or too
small) or NaN. If x is zero, the constant FP_ILOGB0 is returned. If x
is NaN, the constant FP_ILOGBNAN is returned. If x is infinite (or too
large), INT_MAX is returned. If x is too small, INT_MIN is returned.
CONFORMING TO
C99.
SEE ALSO
log(3), logb(3)
COLOPHON
This page is part of release 3.05 of the Linux manpages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/manpages/.
20041031 ILOGB(3)
