time-to-botec

Benchmark sampling in different programming languages
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dmskmax.js (2250B)

      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 isnan = require( '@stdlib/math/base/assert/is-nan' );
     24 var isPositiveZero = require( '@stdlib/math/base/assert/is-positive-zero' );
     25 
     26 
     27 // MAIN //
     28 
     29 /**
     30 * Computes the maximum value of a double-precision floating-point strided array according to a mask.
     31 *
     32 * @param {PositiveInteger} N - number of indexed elements
     33 * @param {Float64Array} x - input array
     34 * @param {integer} strideX - `x` stride length
     35 * @param {Uint8Array} mask - mask array
     36 * @param {integer} strideMask - `mask` stride length
     37 * @returns {number} maximum value
     38 *
     39 * @example
     40 * var Float64Array = require( '@stdlib/array/float64' );
     41 * var Uint8Array = require( '@stdlib/array/uint8' );
     42 *
     43 * var x = new Float64Array( [ 1.0, -2.0, 4.0, 2.0 ] );
     44 * var mask = new Uint8Array( [ 0, 0, 1, 0 ] );
     45 *
     46 * var v = dmskmax( x.length, x, 1, mask, 1 );
     47 * // returns 2.0
     48 */
     49 function dmskmax( N, x, strideX, mask, strideMask ) {
     50 	var max;
     51 	var ix;
     52 	var im;
     53 	var v;
     54 	var i;
     55 
     56 	if ( N <= 0 ) {
     57 		return NaN;
     58 	}
     59 	if ( strideX < 0 ) {
     60 		ix = (1-N) * strideX;
     61 	} else {
     62 		ix = 0;
     63 	}
     64 	if ( strideMask < 0 ) {
     65 		im = (1-N) * strideMask;
     66 	} else {
     67 		im = 0;
     68 	}
     69 	for ( i = 0; i < N; i++ ) {
     70 		if ( mask[ im ] === 0 ) {
     71 			break;
     72 		}
     73 		ix += strideX;
     74 		im += strideMask;
     75 	}
     76 	if ( i === N ) {
     77 		return NaN;
     78 	}
     79 	max = x[ ix ];
     80 	if ( isnan( max ) ) {
     81 		return max;
     82 	}
     83 	i += 1;
     84 	for ( i; i < N; i++ ) {
     85 		ix += strideX;
     86 		im += strideMask;
     87 		if ( mask[ im ] ) {
     88 			continue;
     89 		}
     90 		v = x[ ix ];
     91 		if ( isnan( v ) ) {
     92 			return v;
     93 		}
     94 		if ( v > max || ( v === max && isPositiveZero( v ) ) ) {
     95 			max = v;
     96 		}
     97 	}
     98 	return max;
     99 }
    100 
    101 
    102 // EXPORTS //
    103 
    104 module.exports = dmskmax;