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 }
48