lnf

Evaluate the natural logarithm of a single-precision floating-point number.

Usage

var lnf = require( '@stdlib/math/base/special/lnf' );

lnf( x )

Evaluates the natural logarithm of a single-precision floating-point number.

var v = lnf( 4.0 );
// returns ~1.386

v = lnf( 0.0 );
// returns -Infinity

v = lnf( Infinity );
// returns Infinity

v = lnf( NaN );
// returns NaN

For negative numbers, the natural logarithm is not defined.

var v = lnf( -4.0 );
// returns NaN

Examples

var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var lnf = require( '@stdlib/math/base/special/lnf' );

var x;
var i;

for ( i = 0; i < 100; i++ ) {
    x = round( randu() * 100.0 );
    console.log( 'lnf(%d) = %d', x, lnf( x ) );
}

C APIs

Usage

#include "stdlib/math/base/special/lnf.h"

stdlib_base_lnf( x )

Evaluates the natural logarithm of a single-precision floating-point number.

float v = stdlib_base_lnf( 2.0f );
// returns ~0.693f

The function accepts the following arguments:

x: [in] float input value.

float stdlib_base_lnf( const float x );

Examples

#include "stdlib/math/base/special/lnf.h"
#include <stdlib.h>
#include <stdio.h>

int main( void ) {
    float out;
    float x;
    int i;

    for ( i = 0; i < 100; i++ ) {
        x = ( (float)rand() / (float)RAND_MAX ) * 100.0f;
        out = stdlib_base_lnf( x );
        printf( "lnf(%f) = %f\n", x, out );
    }
}