gcd.js (1819B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 'use strict'; 20 21 // MODULES // 22 23 var isnan = require( './../../../../base/assert/is-nan' ); 24 var isInteger = require( './../../../../base/assert/is-integer' ); 25 var PINF = require( '@stdlib/constants/float64/pinf' ); 26 var NINF = require( '@stdlib/constants/float64/ninf' ); 27 var INT32_MAX = require( '@stdlib/constants/int32/max' ); 28 var bitwise = require( './bitwise_binary_gcd.js' ); 29 var largeIntegers = require( './binary_gcd.js' ); 30 31 32 // MAIN // 33 34 /** 35 * Computes the greatest common divisor (gcd). 36 * 37 * @param {integer} a - integer 38 * @param {integer} b - integer 39 * @returns {integer} greatest common divisor 40 * 41 * @example 42 * var v = gcd( 48, 18 ); 43 * // returns 6 44 * 45 * @example 46 * var v = gcd( 3.14, 18 ); 47 * // returns NaN 48 * 49 * @example 50 * var v = gcd( NaN, 18 ); 51 * // returns NaN 52 */ 53 function gcd( a, b ) { 54 if ( isnan( a ) || isnan( b ) ) { 55 return NaN; 56 } 57 if ( 58 a === PINF || 59 b === PINF || 60 a === NINF || 61 b === NINF 62 ) { 63 return NaN; 64 } 65 if ( !( isInteger( a ) && isInteger( b ) ) ) { 66 return NaN; 67 } 68 if ( a < 0 ) { 69 a = -a; 70 } 71 if ( b < 0 ) { 72 b = -b; 73 } 74 if ( a <= INT32_MAX && b <= INT32_MAX ) { 75 return bitwise( a, b ); 76 } 77 return largeIntegers( a, b ); 78 } 79 80 81 // EXPORTS // 82 83 module.exports = gcd;