log2(), log2f(), log2l()

Compute the base-2 logarithm of a number

Synopsis:

#include <math.h>

double log2( double x );

float log2f( float x );

long double log2l( long double x );

Arguments:

x
The number that you want to compute the base-2 log of.

Library:

libm

Use the -l m option to qcc to link against this library.

Description:

The log2(), log2f(), and log2l() functions compute the base-2 logarithm of x:

log2x

To check for error situations, use feclearexcept() and fetestexcept():

Returns:

The base-2 logarithm of x.

Errors:

FE_DIVBYZERO
The value of x is 0.
FE_INVALID
The finite value of x is less than 0, or x is -Inf.

Classification:

ANSI, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler No
Signal handler No
Thread Yes