NAME

ilogb, ilogbf, ilogbl — extract exponent

SYNOPSIS

#include <math.h>

int
ilogb(double x);

int
ilogbf(float x);

int
ilogbl(long double x);

DESCRIPTION

ilogb() returns x's exponent n, in integer format. ilogb(±infinity) returns INT_MAX, ilogb(NaN) returns FP_ILOGBNAN and ilogb(0) returns FP_ILOGB0. The ilogbf() function is a single precision version of ilogb(). The ilogbl() function is an extended precision version of ilogb().

SEE ALSO

ffs(3), frexp(3)

STANDARDS

IEEE Std 754-1985

HISTORY

The ilogb, ilogbf and ilogbl functions appeared in 4.3BSD, NetBSD 1.1 and OpenBSD 4.5, respectively.