heaviside.js (1807B)
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 Heaviside function. 30 * 31 * @param {number} x - input value 32 * @param {string} [continuity] - continuity option 33 * @returns {number} function value 34 * 35 * @example 36 * var v = heaviside( 3.14 ); 37 * // returns 1.0 38 * 39 * @example 40 * var v = heaviside( -3.14 ); 41 * // returns 0.0 42 * 43 * @example 44 * var v = heaviside( 0.0 ); 45 * // returns NaN 46 * 47 * @example 48 * var v = heaviside( 0.0, 'half-maximum' ); 49 * // returns 0.5 50 * 51 * @example 52 * var v = heaviside( 0.0, 'left-continuous' ); 53 * // returns 0.0 54 * 55 * @example 56 * var v = heaviside( 0.0, 'right-continuous' ); 57 * // returns 1.0 58 * 59 * @example 60 * var v = heaviside( NaN ); 61 * // returns NaN 62 */ 63 function heaviside( x, continuity ) { 64 if ( isnan( x ) ) { 65 return NaN; 66 } 67 if ( x > 0.0 ) { 68 return 1.0; 69 } 70 // Handle `+-0`... 71 if ( x === 0.0 ) { 72 if ( continuity === 'half-maximum' ) { 73 return 0.5; 74 } 75 if ( continuity === 'left-continuous' ) { 76 return 0.0; 77 } 78 if ( continuity === 'right-continuous' ) { 79 return 1.0; 80 } 81 // Default behavior is discontinuity... 82 return NaN; 83 } 84 return 0.0; 85 } 86 87 88 // EXPORTS // 89 90 module.exports = heaviside;