dirac_delta.js (1240B)
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 PINF = require( '@stdlib/constants/float64/pinf' ); 25 26 27 // MAIN // 28 29 /** 30 * Evaluates the Dirac delta function. 31 * 32 * @param {number} x - input value 33 * @returns {number} function value 34 * 35 * @example 36 * var v = diracDelta( 0.0 ); 37 * // returns Infinity 38 * 39 * @example 40 * var v = diracDelta( 3.14 ); 41 * // returns 0.0 42 * 43 * @example 44 * var v = diracDelta( NaN ); 45 * // returns NaN 46 */ 47 function diracDelta( x ) { 48 if ( isnan( x ) ) { 49 return NaN; 50 } 51 if ( x === 0.0 ) { 52 return PINF; 53 } 54 return 0.0; 55 } 56 57 58 // EXPORTS // 59 60 module.exports = diracDelta;