libgomp/testsuite/libgomp.c/omp_orphan.c

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