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log2

Syntax

 
#include <math.h>

double log2(double x);

Description

This function computes the base-2 logarithm of x.

Return Value

The base-2 logarithm of x. If x is zero, a negative infinity is returned and errno is set to ERANGE. If x is negative or +Inf or a NaN, the return value is NaN and errno is set to EDOM.

Portability

ANSI/ISO C No
POSIX No


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  Copyright 2004   by DJ Delorie     Updated Apr 2004