object.js (1577B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2020 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 isInteger = require( './../../is-integer' ).isObject; 24 var sqrt = require( '@stdlib/math/base/special/sqrt' ); 25 var floor = require( '@stdlib/math/base/special/floor' ); 26 27 28 // MAIN // 29 30 /** 31 * Tests if a value is a number object having a value which is a triangular number. 32 * 33 * ## Notes 34 * 35 * - Return values are not reliable for numbers greater than `1125899906842624`. 36 * 37 * @param {*} value - value to test 38 * @returns {boolean} boolean indicating if a value is a number object having a value which is a triangular number 39 * 40 * @example 41 * var bool = isTriangularNumber( 36.0 ); 42 * // returns false 43 * 44 * @example 45 * var bool = isTriangularNumber( new Number( 36.0 ) ); 46 * // returns true 47 */ 48 function isTriangularNumber( value ) { 49 var n; 50 var x; 51 if ( !isInteger( value ) ) { 52 return false; 53 } 54 x = ( 8.0*value.valueOf() ) + 1.0; 55 n = floor( sqrt( x ) + 0.5 ); 56 return n*n === x; 57 } 58 59 60 // EXPORTS // 61 62 module.exports = isTriangularNumber;