ILOGB
Section: Linux Programmer's Manual (3)
Updated: 20041031
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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()
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
feclearexcept(FE_ALL_EXCEPT)
before calling these functions. On return, if
errno
is nonzero or
fetestexcept(FE_INVALID  FE_DIVBYZERO  FE_OVERFLOW  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)
Index
 NAME

 SYNOPSIS

 DESCRIPTION

 ERRORS

 CONFORMING TO

 SEE ALSO

linux.jgfs.net manual pages