log(), logf()

Compute the natural logarithm of a number

Synopsis:

#include <math.h>

double log( double x );

float logf( float x );

Library:

libm

Description:

The log() and logf() functions compute the natural logarithm (base e) of x:

log_e x

A domain error occurs if x is negative. A range error occurs if x is zero.

Returns:

The natural logarithm of x.

Examples:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main( void )
{
    printf( "%f\n", log(.5) );
    
    return EXIT_SUCCESS;
}

produces the output:

-0.693147

Classification:

log() is ANSI; logf() is ANSI (draft)

See also:

errno, exp(), log10(), pow()