Using the reduction clause

[octavio]

Hi
I want to use the reduction clause to parallelize something like this:

Code: Select all


.
.
.
#pragma parallel for ... reduction(+: sum_1,  sum_2, ..., sum_100)
for(i=0; i<N; i++)
{
      if(proposition_1) sum_1++;
      if(proposition_2) sum_2++;
                      ...
      if(proposition_100) sum_100++;
}
.
.
.


and I know the variables sum_i have to be scalars.

Does I have to write down each "if(proposition_i) sum_i ++ "" or is there a better way to do this?

[MarkB]

Are you using scalars just so you can use the reduction clause? If so, it would be neater to use an array and a critical section:

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    .
    .
    .
    #pragma omp parallel private(t_sum) shared (sum)
   {
    #pragma omp for
    for(i=0; i<N; i++)
    {
      for (j=0; j<100;j++){
          if(proposition(j)) t_sum[j]++;
       }
    }
    #pragma omp critical
    {
       for (j=0; j<100;j++){
          sum[j] +=  t_sum[j];
       }
     }
    }
    .
    .
    .