ndarray.native.js (1876B)
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 Float64Array = require( '@stdlib/array/float64' ); 24 var addon = require( './dvarmpn.native.js' ); 25 26 27 // MAIN // 28 29 /** 30 * Computes the variance of a double-precision floating-point strided array provided a known mean and using Neely's correction algorithm. 31 * 32 * @param {PositiveInteger} N - number of indexed elements 33 * @param {number} mean - mean 34 * @param {number} correction - degrees of freedom adjustment 35 * @param {Float64Array} x - input array 36 * @param {integer} stride - stride length 37 * @param {NonNegativeInteger} offset - starting index 38 * @returns {number} variance 39 * 40 * @example 41 * var Float64Array = require( '@stdlib/array/float64' ); 42 * var floor = require( '@stdlib/math/base/special/floor' ); 43 * 44 * var x = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] ); 45 * var N = floor( x.length / 2 ); 46 * 47 * var v = dvarmpn( N, 1.25, 1, x, 2, 1 ); 48 * // returns 6.25 49 */ 50 function dvarmpn( N, mean, correction, x, stride, offset ) { 51 var view; 52 if ( stride < 0 ) { 53 offset += (N-1) * stride; 54 } 55 view = new Float64Array( x.buffer, x.byteOffset+(x.BYTES_PER_ELEMENT*offset), x.length-offset ); // eslint-disable-line max-len 56 return addon( N, mean, correction, view, stride ); 57 } 58 59 60 // EXPORTS // 61 62 module.exports = dvarmpn;