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() returns INT_MAX, ilogb() 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() returns +, and logb(0) returns - with a division by zero exception.
SEE ALSO
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