log1pmx

Evaluate ln(1+x) - x.

Installation

npm install @stdlib/math-base-special-log1pmx

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 );
    }
}

See Also

• @stdlib/math-base/special/ln: evaluate the natural logarithm of a double-precision floating-point number.
• @stdlib/math-base/special/log1p: evaluate the natural logarithm of 1+x.

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.