About stdlib...
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Gamma function.
The gamma function extends the factorial function to real and complex numbers. If n
is a positive integer
,
Generalized to all complex numbers z
, except for nonpositive integers, the gamma function can be expressed as an infinite product
where γ ≈ 0.577216
is the Euler–Mascheroni constant.
npm install @stdlib/math-base-special-gamma
Alternatively,
- To load the package in a website via a
script
tag without installation and bundlers, use the ES Module available on theesm
branch (see README). - If you are using Deno, visit the
deno
branch (see README for usage intructions). - For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the
umd
branch (see README).
The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.
To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.
var gamma = require( '@stdlib/math-base-special-gamma' );
Evaluates the gamma function.
var v = gamma( 4.0 );
// returns 6.0
v = gamma( -1.5 );
// returns ~2.363
v = gamma( -0.5 );
// returns ~-3.545
v = gamma( 0.5 );
// returns ~1.772
v = gamma( 0.0 );
// returns Infinity
v = gamma( -0.0 );
// returns -Infinity
v = gamma( NaN );
// returns NaN
var linspace = require( '@stdlib/array-base-linspace' );
var gamma = require( '@stdlib/math-base-special-gamma' );
var x = linspace( -10.0, 10.0, 100 );
var i;
for ( i = 0; i < x.length; i ) {
console.log( 'x: %d, f(x): %d', x[ i ], gamma( x[ i ] ) );
}
#include "stdlib/math/base/special/gamma.h"
Evaluates the gamma function.
double out = stdlib_base_gamma( 4.0 );
// returns 6.0
out = stdlib_base_gamma( -1.5 );
// returns ~2.363
The function accepts the following arguments:
- x:
[in] double
input value.
double stdlib_base_gamma( const double x );
#include "stdlib/math/base/special/gamma.h"
#include <stdio.h>
int main( void ) {
const double x[] = { 4.0, -1.5, -0.5, 0.5 };
double y;
int i;
for ( i = 0; i < 4; i ) {
y = stdlib_base_gamma( x[ i ] );
printf( "gamma(%lf) = %lf\n", x[ i ], y );
}
}
@stdlib/math-base/special/gamma1pm1
: compute gamma(x 1) - 1.@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.
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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