dmidrange.js (1905B)
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 isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' ); 24 var isNegativeZero = require( '@stdlib/math/base/assert/is-negative-zero' ); 25 var isnan = require( '@stdlib/math/base/assert/is-nan' ); 26 27 28 // MAIN // 29 30 /** 31 * Computes the mid-range of a double-precision floating-point strided array. 32 * 33 * @param {PositiveInteger} N - number of indexed elements 34 * @param {Float64Array} x - input array 35 * @param {integer} stride - stride length 36 * @returns {number} mid-range 37 * 38 * @example 39 * var Float64Array = require( '@stdlib/array/float64' ); 40 * 41 * var x = new Float64Array( [ 1.0, -2.0, 2.0 ] ); 42 * 43 * var v = dmidrange( x.length, x, 1 ); 44 * // returns 0.0 45 */ 46 function dmidrange( N, x, stride ) { 47 var max; 48 var min; 49 var ix; 50 var v; 51 var i; 52 53 if ( N <= 0 ) { 54 return NaN; 55 } 56 if ( N === 1 || stride === 0 ) { 57 return x[ 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 || ( v === min && isNegativeZero( v ) ) ) { 73 min = v; 74 } else if ( v > max || ( v === max && isPositiveZero( v ) ) ) { 75 max = v; 76 } 77 } 78 return ( max+min ) / 2.0; 79 } 80 81 82 // EXPORTS // 83 84 module.exports = dmidrange;