ndarray.js (1718B)
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 // MAIN // 22 23 /** 24 * Computes the arithmetic mean of a double-precision floating-point strided array, ignoring `NaN` values and using ordinary recursive summation. 25 * 26 * @param {PositiveInteger} N - number of indexed elements 27 * @param {Float64Array} x - input array 28 * @param {integer} stride - stride length 29 * @param {NonNegativeInteger} offset - starting index 30 * @returns {number} arithmetic mean 31 * 32 * @example 33 * var Float64Array = require( '@stdlib/array/float64' ); 34 * var floor = require( '@stdlib/math/base/special/floor' ); 35 * 36 * var x = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0, NaN ] ); 37 * var N = floor( x.length / 2 ); 38 * 39 * var v = dnanmeanors( N, x, 2, 1 ); 40 * // returns 1.25 41 */ 42 function dnanmeanors( N, x, stride, offset ) { 43 var ix; 44 var v; 45 var s; 46 var n; 47 var i; 48 49 if ( N <= 0 ) { 50 return NaN; 51 } 52 if ( N === 1 || stride === 0 ) { 53 return x[ offset ]; 54 } 55 ix = offset; 56 s = 0.0; 57 n = 0; 58 for ( i = 0; i < N; i++ ) { 59 v = x[ ix ]; 60 if ( v === v ) { 61 s += v; 62 n += 1; 63 } 64 ix += stride; 65 } 66 return s / n; 67 } 68 69 70 // EXPORTS // 71 72 module.exports = dnanmeanors;