# ilogb(3) [osx man page]

```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.

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.

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```
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