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