gamma1pm1

Compute gamma(x+1) - 1.

Installation

npm install @stdlib/math-base-special-gamma1pm1

Usage

var gamma1pm1 = require( '@stdlib/math-base-special-gamma1pm1' );

gamma1pm1( x )

Computes gamma(x+1) - 1 without cancellation errors for small x and where gamma(x) is the gamma function.

var v = gamma1pm1( 0.2 );
// returns ~-0.082

v = gamma1pm1( -8.5 );
// returns ~-1.0

v = gamma1pm1( 0.0 );
// returns 0.0

v = gamma1pm1( NaN );
// returns NaN

Examples

var randu = require( '@stdlib/random-base-randu' );
var gamma1pm1 = require( '@stdlib/math-base-special-gamma1pm1' );

var x;
var i;

for ( i = 0; i < 100; i++ ) {
    x = (randu()*10.0) - 5.0;
    console.log( 'gamma(%d+1) - 1 = %d', x, gamma1pm1( x ) );
}

See Also

• @stdlib/math-base/special/gamma: gamma function.
• @stdlib/math-base/special/gammainc: incomplete gamma function.
• @stdlib/math-base/special/gammaincinv: inverse incomplete gamma function.
• @stdlib/math-base/special/gammaln: natural logarithm of the gamma function.

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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Copyright

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