Combination

A Combination is a way of selecting members from a group such that order of selection does not matter. This can be contrasted with permutations, where order is accounted for. Combination is usually expressed as n choose k or n items taken k at a time.

mctad.factorial() is used to calculate mctad.combination(); mctad.combination() is used to calculate mctad.pascal().

Assumptions

n and k are non-negative Integers.

Use

mctad.combination(n, k)

Inline Comments

mctad.combination = function(n, k) {

Check that n and k are non-negative Integers.

if (!mctad.isInteger(n) || n < 0 || !mctad.isInteger(k) || k < 0) { return undefined; } if (k > n) { return 0; }

Literal implementation of the (n k) = n!/(k!(n - k)!) formula.

return this.factorial(n)/(this.factorial(k) * this.factorial(n - k)); };