simple-squiggle/node_modules/mathjs/lib/esm/function/arithmetic/invmod.js

57 lines
1.6 KiB
JavaScript

import { factory } from '../../utils/factory.js';
var name = 'invmod';
var dependencies = ['typed', 'config', 'BigNumber', 'xgcd', 'equal', 'smaller', 'mod', 'add', 'isInteger'];
export var createInvmod = /* #__PURE__ */factory(name, dependencies, _ref => {
var {
typed,
config,
BigNumber,
xgcd,
equal,
smaller,
mod,
add,
isInteger
} = _ref;
/**
* Calculate the (modular) multiplicative inverse of a modulo b. Solution to the equation `ax ≣ 1 (mod b)`
* See https://en.wikipedia.org/wiki/Modular_multiplicative_inverse.
*
* Syntax:
*
* math.invmod(a, b)
*
* Examples:
*
* math.invmod(8, 12) // returns NaN
* math.invmod(7, 13) // return 2
* math.invmod(15151, 15122) // returns 10429
*
* See also:
*
* gcd, xgcd
*
* @param {number | BigNumber} a An integer number
* @param {number | BigNumber} b An integer number
* @return {number | BigNumber } Returns an integer number
* where `invmod(a,b)*a ≣ 1 (mod b)`
*/
return typed(name, {
'number, number': invmod,
'BigNumber, BigNumber': invmod
});
function invmod(a, b) {
if (!isInteger(a) || !isInteger(b)) throw new Error('Parameters in function invmod must be integer numbers');
a = mod(a, b);
if (equal(b, 0)) throw new Error('Divisor must be non zero');
var res = xgcd(a, b);
res = res.valueOf();
var [gcd, inv] = res;
if (!equal(gcd, BigNumber(1))) return NaN;
inv = mod(inv, b);
if (smaller(inv, BigNumber(0))) inv = add(inv, b);
return inv;
}
});