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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 | 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 2x 3x 1x 1x 3x 3x 3x 3x 3x | /** * @license Apache-2.0 * * Copyright (c) 2025 The Stdlib Authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ 'use strict'; /** * LAPACK routine to generate a real elementary reflector `H` of order `N` such that applying `H` to a vector `[alpha; x]` zeros out `X`. * * ## Notes * * - `H` is a Householder matrix with the form `H = I - tau * [1; v] * [1, v^T]`, where `tau` is a scalar and `v` is a vector. * - the input vector is `[alpha; x]`, where `alpha` is a scalar and `X` is a real `(n-1)`-element vector. * - the result of applying `H` to `[alpha; x]` is `[beta; 0]`, with `beta` being a scalar and the rest of the vector zeroed. * - if all elements of `X` are zero, then `tau = 0` and `H` is the identity matrix. * - otherwise, `1 <= tau <= 2` * * @module @stdlib/lapack/base/dlarfg * * @example * var Float64Array = require( '@stdlib/array/float64' ); * var dlarfg = require( '@stdlib/lapack/base/dlarfg' ); * * var X = new Float64Array( [ 2.0, 3.0, 4.0 ] ); * var out = new Float64Array( [ 4.0, 0.0 ] ); * * dlarfg( 4, X, 1, out ); * // X => <Float64Array>[ ~0.19, ~0.28, ~0.37 ] * // out => <Float64Array>[ ~-6.7, ~1.6 ] * * @example * var Float64Array = require( '@stdlib/array/float64' ); * var dlarfg = require( '@stdlib/lapack/base/dlarfg' ); * * var X = new Float64Array( [ 2.0, 3.0, 4.0 ] ); * var out = new Float64Array( [ 4.0, 0.0 ] ); * * dlarfg.ndarray( 4, X, 1, 0, out, 1, 0 ); * // X => <Float64Array>[ ~0.19, ~0.28, ~0.37 ] * // out => <Float64Array>[ ~-6.7, ~1.6 ] */ // MODULES // var join = require( 'path' ).join; var tryRequire = require( '@stdlib/utils/try-require' ); var isError = require( '@stdlib/assert/is-error' ); var main = require( './main.js' ); // MAIN // var dlarfg; var tmp = tryRequire( join( __dirname, './native.js' ) ); if ( isError( tmp ) ) { dlarfg = main; } else { dlarfg = tmp; } // EXPORTS // module.exports = dlarfg; |