96 lines
2.6 KiB
JavaScript
96 lines
2.6 KiB
JavaScript
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"use strict";
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.createPermutations = void 0;
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var _number = require("../../utils/number.js");
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var _product = require("../../utils/product.js");
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var _factory = require("../../utils/factory.js");
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var name = 'permutations';
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var dependencies = ['typed', 'factorial'];
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var createPermutations = /* #__PURE__ */(0, _factory.factory)(name, dependencies, function (_ref) {
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var typed = _ref.typed,
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factorial = _ref.factorial;
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/**
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* Compute the number of ways of obtaining an ordered subset of `k` elements
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* from a set of `n` elements.
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*
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* Permutations only takes integer arguments.
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* The following condition must be enforced: k <= n.
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*
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* Syntax:
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*
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* math.permutations(n)
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* math.permutations(n, k)
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*
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* Examples:
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*
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* math.permutations(5) // 120
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* math.permutations(5, 3) // 60
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*
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* See also:
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*
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* combinations, combinationsWithRep, factorial
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*
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* @param {number | BigNumber} n The number of objects in total
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* @param {number | BigNumber} [k] The number of objects in the subset
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* @return {number | BigNumber} The number of permutations
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*/
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return typed(name, {
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'number | BigNumber': factorial,
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'number, number': function numberNumber(n, k) {
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if (!(0, _number.isInteger)(n) || n < 0) {
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throw new TypeError('Positive integer value expected in function permutations');
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}
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if (!(0, _number.isInteger)(k) || k < 0) {
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throw new TypeError('Positive integer value expected in function permutations');
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}
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if (k > n) {
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throw new TypeError('second argument k must be less than or equal to first argument n');
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} // Permute n objects, k at a time
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return (0, _product.product)(n - k + 1, n);
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},
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'BigNumber, BigNumber': function BigNumberBigNumber(n, k) {
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var result, i;
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if (!isPositiveInteger(n) || !isPositiveInteger(k)) {
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throw new TypeError('Positive integer value expected in function permutations');
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}
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if (k.gt(n)) {
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throw new TypeError('second argument k must be less than or equal to first argument n');
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}
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var one = n.mul(0).add(1);
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result = one;
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for (i = n.minus(k).plus(1); i.lte(n); i = i.plus(1)) {
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result = result.times(i);
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}
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return result;
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} // TODO: implement support for collection in permutations
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});
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});
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/**
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* Test whether BigNumber n is a positive integer
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* @param {BigNumber} n
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* @returns {boolean} isPositiveInteger
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*/
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exports.createPermutations = createPermutations;
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function isPositiveInteger(n) {
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return n.isInteger() && n.gte(0);
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}
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