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1 /******************************************************************************
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2 * FILE: omp_reduction.c
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3 * DESCRIPTION:
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4 * OpenMP Example - Combined Parallel Loop Reduction - C/C++ Version
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5 * This example demonstrates a sum reduction within a combined parallel loop
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6 * construct. Notice that default data element scoping is assumed - there
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7 * are no clauses specifying shared or private variables. OpenMP will
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8 * automatically make loop index variables private within team threads, and
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9 * global variables shared.
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10 * AUTHOR: Blaise Barney 5/99
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11 * LAST REVISED: 04/06/05
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12 ******************************************************************************/
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13 #include <omp.h>
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14 #include <stdio.h>
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15 #include <stdlib.h>
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16
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17 int main (int argc, char *argv[]) {
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18
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19 int i, n;
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20 float a[100], b[100], sum;
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21
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22 /* Some initializations */
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23 n = 100;
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24 for (i=0; i < n; i++)
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25 a[i] = b[i] = i * 1.0;
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26 sum = 0.0;
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27
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28 #pragma omp parallel for reduction(+:sum)
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29 for (i=0; i < n; i++)
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30 sum = sum + (a[i] * b[i]);
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31
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32 printf(" Sum = %f\n",sum);
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33
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34 return 0;
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35 }
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