ndarray.js (1818B)
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 double-precision floating-point strided array. 30 * 31 * @param {PositiveInteger} N - number of indexed elements 32 * @param {Float64Array} x - input array 33 * @param {integer} stride - stride length 34 * @param {NonNegativeInteger} offset - starting index 35 * @returns {number} range 36 * 37 * @example 38 * var Float64Array = require( '@stdlib/array/float64' ); 39 * var floor = require( '@stdlib/math/base/special/floor' ); 40 * 41 * var x = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] ); 42 * var N = floor( x.length / 2 ); 43 * 44 * var v = drange( N, x, 2, 1 ); 45 * // returns 6.0 46 */ 47 function drange( N, x, stride, offset ) { 48 var max; 49 var min; 50 var ix; 51 var v; 52 var i; 53 54 if ( N <= 0 ) { 55 return NaN; 56 } 57 if ( N === 1 || stride === 0 ) { 58 if ( isnan( x[ offset ] ) ) { 59 return NaN; 60 } 61 return 0.0; 62 } 63 ix = offset; 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 = drange;