/******************************************************************************
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/******************************************************************************
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* FILE: omp_reduction.c
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* FILE: omp_reduction.c
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* DESCRIPTION:
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* DESCRIPTION:
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* OpenMP Example - Combined Parallel Loop Reduction - C/C++ Version
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* OpenMP Example - Combined Parallel Loop Reduction - C/C++ Version
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* This example demonstrates a sum reduction within a combined parallel loop
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* This example demonstrates a sum reduction within a combined parallel loop
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* construct. Notice that default data element scoping is assumed - there
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* construct. Notice that default data element scoping is assumed - there
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* are no clauses specifying shared or private variables. OpenMP will
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* are no clauses specifying shared or private variables. OpenMP will
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* automatically make loop index variables private within team threads, and
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* automatically make loop index variables private within team threads, and
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* global variables shared.
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* global variables shared.
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* AUTHOR: Blaise Barney 5/99
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* AUTHOR: Blaise Barney 5/99
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* LAST REVISED: 04/06/05
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* LAST REVISED: 04/06/05
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******************************************************************************/
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******************************************************************************/
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#include <omp.h>
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#include <omp.h>
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#include <stdio.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdlib.h>
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int main (int argc, char *argv[]) {
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int main (int argc, char *argv[]) {
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int i, n;
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int i, n;
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float a[100], b[100], sum;
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float a[100], b[100], sum;
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/* Some initializations */
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/* Some initializations */
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n = 100;
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n = 100;
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for (i=0; i < n; i++)
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for (i=0; i < n; i++)
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a[i] = b[i] = i * 1.0;
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a[i] = b[i] = i * 1.0;
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sum = 0.0;
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sum = 0.0;
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#pragma omp parallel for reduction(+:sum)
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#pragma omp parallel for reduction(+:sum)
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for (i=0; i < n; i++)
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for (i=0; i < n; i++)
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sum = sum + (a[i] * b[i]);
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sum = sum + (a[i] * b[i]);
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printf(" Sum = %f\n",sum);
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printf(" Sum = %f\n",sum);
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return 0;
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return 0;
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}
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}
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