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1 /******************************************************************************
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2 * FILE: omp_orphan.c
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3 * DESCRIPTION:
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4 * OpenMP Example - Parallel region with an orphaned directive - C/C++ Version
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5 * This example demonstrates a dot product being performed by an orphaned
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6 * loop reduction construct. Scoping of the reduction variable is critical.
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7 * AUTHOR: Blaise Barney 5/99
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8 * LAST REVISED: 04/06/05
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9 ******************************************************************************/
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10 #include <omp.h>
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11 #include <stdio.h>
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12 #include <stdlib.h>
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13 #define VECLEN 100
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14
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15 float a[VECLEN], b[VECLEN], sum;
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16
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17 float dotprod ()
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18 {
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19 int i,tid;
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20
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21 tid = omp_get_thread_num();
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22 #pragma omp for reduction(+:sum)
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23 for (i=0; i < VECLEN; i++)
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24 {
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25 sum = sum + (a[i]*b[i]);
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26 printf(" tid= %d i=%d\n",tid,i);
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27 }
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28
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29 return(sum);
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30 }
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31
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32
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33 int main (int argc, char *argv[])
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34 {
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35 int i;
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36
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37 for (i=0; i < VECLEN; i++)
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38 a[i] = b[i] = 1.0 * i;
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39 sum = 0.0;
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40
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41 #pragma omp parallel
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42 sum = dotprod();
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43
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44 printf("Sum = %f\n",sum);
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45
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46 return 0;
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47 }
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