ILOGB(3) | FreeBSD Library Functions Manual | ILOGB(3) |
NAME
ilogb, ilogbf, ilogbl, logb, logbf, logbl — extract exponentLIBRARY
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.
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
December 16, 2007 | FreeBSD |