range.js (1588B)
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 isnan = require( '@stdlib/math/base/assert/is-nan' ); 24 25 26 // MAIN // 27 28 /** 29 * Computes the range of a strided array. 30 * 31 * @param {PositiveInteger} N - number of indexed elements 32 * @param {NumericArray} x - input array 33 * @param {integer} stride - stride length 34 * @returns {number} range 35 * 36 * @example 37 * var x = [ 1.0, -2.0, 2.0 ]; 38 * var N = x.length; 39 * 40 * var v = range( N, x, 1 ); 41 * // returns 4.0 42 */ 43 function range( N, x, stride ) { 44 var max; 45 var min; 46 var ix; 47 var v; 48 var i; 49 50 if ( N <= 0 ) { 51 return NaN; 52 } 53 if ( N === 1 || stride === 0 ) { 54 if ( isnan( x[ 0 ] ) ) { 55 return NaN; 56 } 57 return 0.0; 58 } 59 if ( stride < 0 ) { 60 ix = (1-N) * stride; 61 } else { 62 ix = 0; 63 } 64 min = x[ ix ]; 65 max = min; 66 for ( i = 1; i < N; i++ ) { 67 ix += stride; 68 v = x[ ix ]; 69 if ( isnan( v ) ) { 70 return v; 71 } 72 if ( v < min ) { 73 min = v; 74 } else if ( v > max ) { 75 max = v; 76 } 77 } 78 return max - min; 79 } 80 81 82 // EXPORTS // 83 84 module.exports = range;