51 lines
980 B
Fortran
51 lines
980 B
Fortran
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program main
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use openacc
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implicit real(4) (A-H,O-Z)
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integer, parameter :: NN = 1024
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integer, parameter :: NM = 1024
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real(4) A(NN,NM), Anew(NN,NM)
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iter_max = 1000
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tol = 1.0e-6
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error = 1.0
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A(1,:) = 1.0
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A(2:NN,:) = 0.0
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Anew(1,:) = 1.0
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Anew(2:NN,:) = 0.0
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print 100,NN,NM
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call cpu_time(t1)
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iter = 0
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do while ( (error > tol) .and. (iter < iter_max) )
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error = 0.0
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!$acc kernels
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do j = 2, NM-1
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do i = 2, NN-1
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Anew(i,j) = 0.25 * ( A(i+1,j) + A(i-1,j) + &
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A(i,j-1) + A(i,j+1) )
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error = max( error, abs(Anew(i,j) - A(i,j)) )
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end do
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end do
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!$acc end kernels
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!$acc kernels
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do j = 2, NM-1
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do i = 2, NN-1
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A(i,j) = Anew(i,j)
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end do
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end do
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!$acc end kernels
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if(mod(iter,100) == 0) print 101,iter,error
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iter = iter + 1
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end do
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call cpu_time(t2)
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print 102,t2-t1
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100 format("Jacobi relaxation Calculation: ",i4," x ",i4," mesh")
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101 format(2x,i4,2x,f9.6)
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102 format("total: ",f9.6," s")
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end program
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