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PROGRAM TEST
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IMPLICIT NONE
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C
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INTEGER LDA, LDAF, LDB, LDIWRK, LDWORK, LDX
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INTEGER N, NRHS
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PARAMETER (N = 4)
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PARAMETER (LDA = N)
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PARAMETER (LDAF = LDA)
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PARAMETER (LDB = N)
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PARAMETER (LDIWRK = N)
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PARAMETER (LDX = N)
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PARAMETER (LDWORK = 3 * N)
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PARAMETER (NRHS = 1)
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C
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DOUBLE PRECISION A(LDA,N), AF(LDAF,N), B(LDB,NRHS)
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DOUBLE PRECISION BERR(NRHS), FERR(NRHS), RCOND, SCALE(N)
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DOUBLE PRECISION WORK(LDWORK), X(LDX,NRHS)
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INTEGER ICOL, INFO, IROW, IWORK(LDIWRK)
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CHARACTER*1 EQUED
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C
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EXTERNAL DPOSVX
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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,
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$ -1.0D0, 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 DPOSVX ('EQUILIBRATE A', 'UPPER TRIANGLE OF A STORED',
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$ N, NRHS, A, LDA, AF, LDAF, EQUED, SCALE,
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$ B, LDB, X, LDX, RCOND, FERR, BERR, WORK,
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$ IWORK, INFO)
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IF (INFO .NE. 0) THEN
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PRINT 1050, INFO
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IF (INFO .EQ. (N + 1)) THEN
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PRINT 1060
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STOP 1
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END IF
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STOP 2
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END IF
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PRINT 1070
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PRINT 1040, X
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PRINT 1080, 1.0D0 / RCOND
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IF (EQUED .EQ. 'N') PRINT 1090
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IF (EQUED .EQ. 'R') PRINT 1100
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IF (EQUED .EQ. 'C') PRINT 1110
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IF (EQUED .EQ. 'B') PRINT 1120
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PRINT 1130, (IROW, BERR(IROW), IROW = 1, NRHS)
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PRINT 1140, (IROW, FERR(IROW), IROW = 1, NRHS)
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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, F6.2)
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1050 FORMAT (1X, 'Error solving Ax=b, INFO = ', I5)
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1060 FORMAT (1X, 'Matrix is singular to working precision.')
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1070 FORMAT (/1X, 'x:')
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1080 FORMAT (/1X, 'Estimated condition number of A: ', F7.2)
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1090 FORMAT (1X, 'No equilibration was required for A.')
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1100 FORMAT (1X, 'Row equilibration was done on A.')
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1110 FORMAT (1X, 'Column equilibration was done on A.')
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1120 FORMAT (1X, 'Row and column equilibration was done on A.')
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1130 FORMAT (/1X, 'Backward error for system #', I1, ': ',
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$ E12.6)
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1140 FORMAT (1X, 'Forward error for system #', I1, ': ', E12.6)
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C
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END
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