ILOGB(3) BSD Library Functions Manual ILOGB(3)NAME
ilogb -- return exponent as an integer value
SYNOPSIS
#include <math.h>
int
ilogb(double x);
int
ilogbl(long double x);
int
ilogbf(float x);
DESCRIPTION
The ilogb() functions return the exponent of x as a signed integer value.
SPECIAL VALUES
ilogb(+-0) returns FP_ILOGB0.
ilogb(+-infinity) returns INT_MAX.
ilogb(x) returns FP_ILOGBNAN if x is a NaN.
A range error may occur if x is 0, +-infinity, or a nan.
The special return values FP_ILOGB0 and FP_ILOGBNAN are defined in math.h, and may differ between platforms. INT_MAX is defined in limits.h.
SEE ALSO math(3)STANDARDS
The ilogb() functions conform to ISO/IEC 9899:2011.
BSD December 11, 2006 BSD
Check Out this Related Man Page
ILOGB(3) BSD Library Functions Manual ILOGB(3)NAME
ilogb, ilogbf, ilogbl, logb, logbf, logbl -- extract exponent
LIBRARY
Math Library (libm, -lm)
SYNOPSIS
#include <math.h>
int
ilogb(double x);
int
ilogbf(float x);
int
ilogbl(long double x);
double
logb(double x);
float
logbf(float x);
long double
logbl(long double x);
DESCRIPTION
ilogb(), ilogbf() and ilogbl() return x's exponent in integer format. ilogb(+-infinity) returns INT_MAX, ilogb(+-NaN) returns FP_ILOGBNAN,
and ilogb(0) returns FP_ILOGB0.
logb(x), logbf(x), and logbl(x) return x's exponent in floating-point format with the same precision as x. logb(+-infinity) returns +infin-
ity, and logb(0) returns -infinity with a division by zero exception.
SEE ALSO frexp(3), ieee(3), math(3), scalbn(3)STANDARDS
The ilogb(), ilogbf(), ilogbl(), logb(), logbf(), and logbl() routines conform to ISO/IEC 9899:1999 (``ISO C99''). The latter three imple-
ment the logb function recommended by IEEE Std 754-1985.
HISTORY
Function First Appeared In
logb() 4.3BSD
ilogb() FreeBSD 1.1.5
ilogbf() FreeBSD 2.0
logbf() FreeBSD 2.0
ilogbl() FreeBSD 5.4
logbl() FreeBSD 8.0
BSD December 16, 2007 BSD