93 lines
1.9 KiB
JavaScript
93 lines
1.9 KiB
JavaScript
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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MODULES //
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var abs = require( '@stdlib/math/base/special/abs' );
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// VARIABLES //
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var M = 6;
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// MAIN //
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/**
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* Computes the sum of absolute values.
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*
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* @param {PositiveInteger} N - number of values to sum
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* @param {Float64Array} x - input array
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* @param {integer} stride - `x` stride length
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* @param {NonNegativeInteger} offset - starting `x` index
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* @returns {number} sum
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*
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* @example
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* var Float64Array = require( '@stdlib/array/float64' );
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*
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* var x = new Float64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0 ] );
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*
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* var s = dasum( x.length, x, 1, 0 );
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* // returns 15.0
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*/
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function dasum( N, x, stride, offset ) {
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var sum;
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var ix;
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var m;
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var i;
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sum = 0.0;
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if ( N <= 0 ) {
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return sum;
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}
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ix = offset;
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// Use unrolled loops if the stride is equal to `1`...
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if ( stride === 1 ) {
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m = N % M;
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// If we have a remainder, run a clean-up loop...
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if ( m > 0 ) {
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for ( i = 0; i < m; i++ ) {
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sum += abs( x[ix] );
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ix += stride;
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}
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}
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if ( N < M ) {
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return sum;
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}
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for ( i = m; i < N; i += M ) {
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sum += abs( x[ix] ) + abs( x[ix+1] ) + abs( x[ix+2] ) + abs( x[ix+3] ) + abs( x[ix+4] ) + abs( x[ix+5] ); // eslint-disable-line max-len
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ix += M;
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}
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return sum;
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}
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for ( i = 0; i < N; i++ ) {
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sum += abs( x[ix] );
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ix += stride;
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}
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return sum;
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}
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// EXPORTS //
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module.exports = dasum;
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