gamma1pm1

Compute gamma(x+1) - 1.

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 ) );
}