enhancedmath/lib/Probability/combination.js

This package contains some enhanced mathematical operations

import factorial from '../factorial';
/**
 * Calculates the probability of a combination with a population of n and a sample size r
 * @param {number} n The size of the population
 * @param {number} r The sample size
 * @returns {number} The amount of possible combinations
 */
const combination = (n, r) => {
    if (0 <= r && r <= n) {
        if (factorial(n) && factorial(r) && factorial(n - r)) {
            return factorial(n) / (factorial(r) * factorial(n - r));
        }
        return undefined;
    }
    return undefined;
};
export default combination;