@stdlib/math-base-special-binomcoef NPM

Binomial Coefficient

$NPM version$ $Build Status$ $Coverage Status$

Compute the binomial coefficient.

The binomial coefficient of two nonnegative integers n and k is defined as

The binomial coefficient can be generalized to negative integers n as follows:

Installation

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

Usage

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

binomcoef( n, k )

Evaluates the binomial coefficient of two integers n and k.

var v = binomcoef( 8, 2 );
// returns 28

v = binomcoef( 0, 0 );
// returns 1

v = binomcoef( -4, 2 );
// returns 10

v = binomcoef( 5, 3 );
// returns 10

v = binomcoef( NaN, 3 );
// returns NaN

v = binomcoef( 5, NaN );
// returns NaN

v = binomcoef( NaN, NaN );
// returns NaN

For negative k, the function returns 0.

var v = binomcoef( 2, -1 );
// returns 0

v = binomcoef( -3, -1 );
// returns 0

The function returns NaN for non-integer n or k.

var v = binomcoef( 2, 1.5 );
// returns NaN

v = binomcoef( 5.5, 2 );
// returns NaN

Examples

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

var n;
var k;
var i;

for ( i = 0; i < 100; i++ ) {
    n = round( (randu()*30.0) - 10.0 );
    k = round( randu()*20.0 );
    console.log( '%d choose %d = %d', n, k, binomcoef( n, k ) );
}

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.