Computes the binomial coefficient.
The binomial coefficient of two non-negative integers n and k is defined as
It can be generalized for any two real numbers n and k as follows
where Γ denotes the Gamma function and Beta is the Beta function.
$ npm install math-binomcoefvar binomcoef = require( 'math-binomcoef' );Computes the Binomial coefficient.
var val = binomcoef( 8, 2 );
// returns 28
val = binomcoef( 0, 0 );
// returns 1
val = binomcoef( -4, 2 );
// returns 10
val = binomcoef( 2, -1 );
// returns 0
val = binomcoef( 3, 1.5 );
// returns ~3.395Instead of evaluating the factorial form, which is inefficient and prone to overflow for large inputs arguments, this module computes the following multiplicative representation of the binomial coefficient for integer arguments
For non-integer inputs, the function computes - ln( n + 1 ) - ln( Beta( n - k + 1, k + 1 ) ) and returns the power of this value to base e.
var binomcoef = require( 'math-binomcoef' );
for ( var x = 5; x > 0; x-- ) {
for ( var y = 0; y < 5; y++ ) {
console.log( 'x: %d, \t y: %d, \t f(x,y): %d', x, y, binomcoef( x, y ) );
}
}To run the example code from the top-level application directory,
$ node ./examples/index.jsThis repository uses tape for unit tests. To run the tests, execute the following command in the top-level application directory:
$ make testAll new feature development should have corresponding unit tests to validate correct functionality.
This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:
$ make test-covIstanbul creates a ./reports/coverage directory. To access an HTML version of the report,
$ make view-covThis repository uses Testling for browser testing. To run the tests in a (headless) local web browser, execute the following command in the top-level application directory:
$ make test-browsersTo view the tests in a local web browser,
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