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PROGRAM TEST
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IMPLICIT NONE
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C
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INTEGER LDA, LDB, N, NRHS
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PARAMETER (N = 4)
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PARAMETER (LDA = N)
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PARAMETER (LDB = N)
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PARAMETER (NRHS = 1)
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C
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DOUBLE PRECISION A(LDA,N), B(LDB,NRHS)
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INTEGER ICOL, INFO, IROW
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C
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EXTERNAL DPOSV
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C
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C Initialize the array A to store in symmetric form the 4x4
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C symmetric positive definite matrix A shown below.
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C Initialize the array B to store the right hand side
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C vector b shown below.
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C
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C 2 -1 0 0 6
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C A = -1 2 -1 0 b = 12
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C 0 -1 2 -1 12
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C 0 0 -1 2 6
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C
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DATA A / 2.0D0, 3*8D8, -1.0D0, 2.0D0, 2*8D8, 0.0D0, -1.0D0,
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$ 2.0D0, 8D8, 0.0D0, 0.0D0, -1.0D0, 2.0D0 /
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DATA B / 6.0D0, 1.2D1, 1.2D1, 6.0D0 /
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C
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C Print the initial values of the arrays.
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C
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PRINT 1000
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DO 100, IROW = 1, N
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PRINT 1010, (A(ICOL,IROW), ICOL = 1, IROW - 1),
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$ (A(IROW,ICOL), ICOL = IROW, N)
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100 CONTINUE
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PRINT 1020
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PRINT 1010, ((A(IROW,ICOL), ICOL = 1, N), IROW = 1, LDA)
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PRINT 1030
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PRINT 1040, B
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C
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C Solve Ax=b and print the solution.
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C
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CALL DPOSV ('UPPER TRIANGLE OF A STORED', N, NRHS, A, LDA,
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$ B, LDB, INFO)
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IF (INFO .NE. 0) THEN
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PRINT 1050, INFO
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STOP 1
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END IF
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PRINT 1060
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PRINT 1040, B
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C
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1000 FORMAT (1X, 'A in full form:')
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1010 FORMAT (4(3X, F6.3))
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1020 FORMAT (/1X, 'A in symmetric form: (* in unused elements)')
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1030 FORMAT (/1X, 'b:')
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1040 FORMAT (1X, F6.3)
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1050 FORMAT (1X, 'Error solving Ax=b, INFO = ', I5)
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1060 FORMAT (/1X, 'x:')
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C
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END
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