mathjs/test/function/probability/multinomial.test.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser and offers an integrated solution to work with numbers, big numbers, complex numbers, units, and matrices.

var assert = require('assert'),
error = require('../../../lib/error/index'),
math = require('../../../index'),
multinomial = math.multinomial,
_ = require('underscore');

describe('multinomial', function() {

  it('should calculate the multinomial of an array of numbers', function() {
    assert.equal(multinomial([1,2,1]), 12);
    assert.equal(multinomial([4,2,1]), 105);
    assert.equal(multinomial([4,4]), 70);
  });

  it('should calculate the multinomial of n items taken k at a time with BigNumbers', function() {
    assert.equal(_.isEqual(multinomial([math.bignumber(3), math.bignumber(4), math.bignumber(5)]), math.bignumber(27720)),true);
    assert.deepEqual(multinomial([math.bignumber(10), math.bignumber(1), math.bignumber(2)]), math.bignumber(858));
  });

  it('should not work with non-integer and negative input', function() {
    assert.throws(function() {multinomial([0.5,3])}, TypeError);
      assert.throws(function() {multinomial([math.bignumber(3), math.bignumber(0.5)])}, TypeError);
      assert.throws(function() {multinomial([math.bignumber(3.5), math.bignumber(-3)])}, TypeError);
      assert.throws(function() {multinomial([math.bignumber(3.5), 1/3])}, TypeError);
    });

  it('should not work with the wrong number or type of arguments', function() {
      assert.throws(function() {multinomial(5, 3, 2)});
      assert.throws(function() {multinomial(true, "hello world")});
  });

});