@stdlib/math-base-special-logaddexp
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    0.0.5 • Public • Published

    logaddexp

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    Evaluates the natural logarithm of exp(x) + exp(y).

    Log-domain computations are commonly used to increase accuracy and avoid underflow and overflow when very small or very large numbers are represented directly as limited-precision, floating-point numbers. For example, in statistics, evaluating logaddexp() is useful when probabilities are so small as to exceed the normal range of floating-point numbers.

    Installation

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

    Usage

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

    logaddexp( x, y )

    Evaluates the natural logarithm of exp(x) + exp(y).

    var v = logaddexp( 90.0, 90.0 );
    // returns ~90.6931
    
    v = logaddexp( -20.0, 90.0 );
    // returns 90.0
    
    v = logaddexp( 0.0, -100.0 );
    // returns ~3.7201e-44
    
    v = logaddexp( NaN, 1.0 );
    // returns NaN

    Examples

    var incrspace = require( '@stdlib/array-incrspace' );
    var logaddexp = require( '@stdlib/math-base-special-logaddexp' );
    
    var x;
    var v;
    var i;
    var j;
    
    x = incrspace( -100.0, 100.0, 1.0 );
    for ( i = 0; i < x.length; i++ ) {
        for ( j = i; j < x.length; j++ ) {
            v = logaddexp( x[ i ], x[ j ] );
            console.log( 'x: %d, y: %d, f(x, y): %d', x[ i ], x[ j ], v );
        }
    }

    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.

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    License

    See LICENSE.

    Copyright

    Copyright © 2016-2021. The Stdlib Authors.

    Install

    npm i @stdlib/math-base-special-logaddexp

    Homepage

    stdlib.io

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    Version

    0.0.5

    License

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