48 lines
1.8 KiB
Plaintext
48 lines
1.8 KiB
Plaintext
PROGRAM JAC
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PARAMETER (L=8, ITMAX=20)
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REAL A(L,L), EPS, MAXEPS, B(L,L)
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CDVM$ DISTRIBUTE ( BLOCK, BLOCK) :: A
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CDVM$ ALIGN B(I,J) WITH A(I,J)
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C arrays A and B with block distribution
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PRINT *, '********** TEST_JACOBI **********'
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MAXEPS = 0.5E - 7
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CDVM$ PARALLEL (J,I) ON A(I, J)
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C nest of two parallel loops, iteration (i,j) will be executed on
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C processor, which is owner of element A(i,j)
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DO 1 J = 1, L
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DO 1 I = 1, L
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A(I, J) = 0.
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IF(I.EQ.1 .OR. J.EQ.1 .OR. I.EQ.L .OR. J.EQ.L) THEN
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B(I, J) = 0.
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ELSE
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B(I, J) = ( 1. + I + J )
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ENDIF
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1 CONTINUE
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DO 2 IT = 1, ITMAX
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EPS = 0.
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CDVM$ PARALLEL (J, I) ON A(I, J), REDUCTION ( MAX( EPS ))
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C variable EPS is used for calculation of maximum value
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DO 21 J = 2, L-1
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DO 21 I = 2, L-1
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EPS = MAX ( EPS, ABS( B( I, J) - A( I, J)))
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A(I, J) = B(I, J)
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21 CONTINUE
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CDVM$ PARALLEL (J, I) ON B(I, J), SHADOW_RENEW (A)
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C Copying shadow elements of array A from
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C neighbouring processors before loop execution
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DO 22 J = 2, L-1
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DO 22 I = 2, L-1
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B(I, J) = (A( I-1, J ) + A( I, J-1 ) + A( I+1, J)+
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* A( I, J+1 )) / 4
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22 CONTINUE
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PRINT 200, IT, EPS
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200 FORMAT(' IT = ',I4, ' EPS = ', E14.7)
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IF ( EPS . LT . MAXEPS ) GO TO 3
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2 CONTINUE
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3 OPEN (3, FILE='JAC.DAT', FORM='FORMATTED', STATUS='UNKNOWN')
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WRITE (3,*) B
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CLOSE (3)
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END
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