# logbl(3) [netbsd man page]

```IEEE_TEST(3)						   BSD Library Functions Manual 					      IEEE_TEST(3)

NAME
logb, logbf, logbl, scalb, scalbf, significand, significandf -- IEEE test functions

LIBRARY
Math Library (libm, -lm)

SYNOPSIS
#include <math.h>

double
logb(double x);

float
logbf(float x);

long double
logbl(long double x);

double
scalb(double x, double n);

float
scalbf(float x, float n);

double
significand(double x);

float
significandf(float x);

DESCRIPTION
These functions allow users to test conformance to IEEE Std 754-1985.  Their use is not otherwise recommended.

logb(x) returns x's exponent n, a signed integer converted to double-precision floating-point.  logb(+-infinity) = +infinity; logb(0) =
-infinity with a division by zero exception.

scalbn(x, n) returns x*(2**n) computed by exponent manipulation.

significand(x) returns sig, where x := sig * 2**n with 1 <= sig < 2.  significand(x) is not defined when x is 0, +-infinity, or NaN.

math(3)

STANDARDS
IEEE Std 754-1985

BSD								  August 3, 2011							       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```
Man Page