scumaxabs.js (2147B)
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 isnanf = require( '@stdlib/math/base/assert/is-nanf' ); 24 var abs = require( '@stdlib/math/base/special/abs' ); 25 26 27 // MAIN // 28 29 /** 30 * Computes the cumulative maximum absolute value of single-precision floating-point strided array elements. 31 * 32 * @param {PositiveInteger} N - number of indexed elements 33 * @param {Float32Array} x - input array 34 * @param {integer} strideX - `x` stride length 35 * @param {Float32Array} y - output array 36 * @param {integer} strideY - `y` stride length 37 * @returns {Float32Array} output array 38 * 39 * @example 40 * var Float32Array = require( '@stdlib/array/float32' ); 41 * 42 * var x = new Float32Array( [ 1.0, -2.0, 2.0 ] ); 43 * var y = new Float32Array( x.length ); 44 * var N = x.length; 45 * 46 * var v = scumaxabs( N, x, 1, y, 1 ); 47 * // returns <Float32Array>[ 1.0, 2.0, 2.0 ] 48 */ 49 function scumaxabs( N, x, strideX, y, strideY ) { 50 var max; 51 var ix; 52 var iy; 53 var v; 54 var i; 55 56 if ( N <= 0 ) { 57 return y; 58 } 59 if ( strideX < 0 ) { 60 ix = (1-N) * strideX; 61 } else { 62 ix = 0; 63 } 64 if ( strideY < 0 ) { 65 iy = (1-N) * strideY; 66 } else { 67 iy = 0; 68 } 69 max = abs( x[ ix ] ); 70 y[ iy ] = max; 71 72 iy += strideY; 73 i = 1; 74 if ( isnanf( max ) === false ) { 75 for ( i; i < N; i++ ) { 76 ix += strideX; 77 v = abs( x[ ix ] ); 78 if ( isnanf( v ) ) { 79 max = v; 80 break; 81 } 82 if ( v > max ) { 83 max = v; 84 } 85 y[ iy ] = max; 86 iy += strideY; 87 } 88 } 89 if ( isnanf( max ) ) { 90 for ( i; i < N; i++ ) { 91 y[ iy ] = max; 92 iy += strideY; 93 } 94 } 95 return y; 96 } 97 98 99 // EXPORTS // 100 101 module.exports = scumaxabs;