log1pmx

Evaluate ln(1+x) - x.

Usage

var log1pmx = require( '@stdlib/math/base/special/log1pmx' );

log1pmx( x )

Evaluates ln(1+x) - x.

var v = log1pmx( 1.1 );
// returns ~-0.358

v = log1pmx( 0.99 );
// returns ~-0.302

v = log1pmx( -0.99 );
// returns ~-3.615

v = log1pmx( -1.1 );
// returns NaN

v = log1pmx( NaN );
// returns NaN

Examples

var incrspace = require( '@stdlib/array/base/incrspace' );
var log1pmx = require( '@stdlib/math/base/special/log1pmx' );

var x = incrspace( 0.0, 10.0, 0.01 );

var i;
for ( i = 0; i < x.length; i++ ) {
    console.log( 'x: %d, f(x): %d', x[ i ], log1pmx( x[ i ] ) );
}

C APIs

Usage

#include "stdlib/math/base/special/log1pmx.h"

stdlib_base_log1pmx( x )

Evaluates ln(1+x) - x.

double out = stdlib_base_log1pmx( 1.1 );
// returns ~-0.358

The function accepts the following arguments:

x: [in] double input value.

double stdlib_base_log1pmx( const double x );

Examples

#include "stdlib/math/base/special/log1pmx.h"
#include <stdlib.h>
#include <stdio.h>

int main( void ) {
    double x;
    double v;
    int i;
    
    for ( i = 0; i < 100; i++ ) {
        x = ( (double)rand() / (double)RAND_MAX ) * 10.0;
        v = stdlib_base_log1pmx( x );
        printf( "x: %lf, f(x): %lf\n", x, v );
    }
}