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ILOGB(3) FreeBSD 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 +infinity,
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 implement 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
FreeBSD 14.0-RELEASE-p6 December 16, 2007 FreeBSD 14.0-RELEASE-p6