Basic HTML version of Foils prepared August 29 98

Foil 46 Good Reductions

From Designing and Building Parallel Programs 2: openMP Shared Memory Programming Language DoD Modernization Tutorial -- 1995-1998. by Ian Foster, Gina Goff, Ehtesham Hayder, Chuck Koelbel(Some foils prepared by Kuck & Associates, Inc.)
1 Correct reduction:
2 c$omp parallel private(suml,i)
3 c$omp& shared(sum,a,n)
4 suml = 0.0
5 c$omp do
6 do 10 i=1,n
7 10 suml = suml + a(i)
8 c$omp critical
9 sum = sum + suml
10 c$omp end critical
11 c$omp end parallel
12 Using Reduction does the same:
13 c$omp parallel private(i)
14 c$omp& shared(a,n)
15 c$omp& reduction(+:sum)
16 c$omp do
17 do 10 i=1,n
18 10 sum = sum + a(i)
19 c$omp end parallel
in Table To:

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