main.js (1397B)
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 25 26 // MAIN // 27 28 /** 29 * Evaluates the Kronecker delta. 30 * 31 * @param {number} i - input value 32 * @param {number} j - input value 33 * @returns {number} function value 34 * 35 * @example 36 * var v = kroneckerDelta( 3.14, 3.14 ); 37 * // returns 1.0 38 * 39 * @example 40 * var v = kroneckerDelta( 3.14, 0.0 ); 41 * // returns 0.0 42 * 43 * @example 44 * var v = kroneckerDelta( NaN, 3.14 ); 45 * // returns NaN 46 * 47 * @example 48 * var v = kroneckerDelta( 3.14, NaN ); 49 * // returns NaN 50 * 51 * @example 52 * var v = kroneckerDelta( NaN, NaN ); 53 * // returns NaN 54 */ 55 function kroneckerDelta( i, j ) { 56 if ( isnan( i ) || isnan( j ) ) { 57 return NaN; 58 } 59 if ( i === j ) { 60 return 1.0; 61 } 62 return 0.0; 63 } 64 65 66 // EXPORTS // 67 68 module.exports = kroneckerDelta;