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gamma1pm1
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Compute
gamma(x+1) - 1.
bash
npm install @stdlib/math-base-special-gamma1pm1
javascript
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][@stdlib/math/base/special/gamma].
javascript
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
javascript
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 ) );
}
@stdlib/math-base/special/gamma][@stdlib/math/base/special/gamma]: gamma function.
- [@stdlib/math-base/special/gammainc][@stdlib/math/base/special/gammainc]: incomplete gamma function.
- [@stdlib/math-base/special/gammaincinv][@stdlib/math/base/special/gammaincinv]: inverse incomplete gamma function.
- [@stdlib/math-base/special/gammaln][@stdlib/math/base/special/gammaln]: natural logarithm of the gamma function.
