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187 lines
7.7 KiB
Fortran
187 lines
7.7 KiB
Fortran
*DECK DTIN
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SUBROUTINE DTIN (N, NELT, IA, JA, A, ISYM, SOLN, RHS, IUNIT, JOB)
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C***BEGIN PROLOGUE DTIN
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C***PURPOSE Read in SLAP Triad Format Linear System.
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C Routine to read in a SLAP Triad format matrix and right
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C hand side and solution to the system, if known.
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C***LIBRARY SLATEC (SLAP)
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C***CATEGORY N1
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C***TYPE DOUBLE PRECISION (STIN-S, DTIN-D)
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C***KEYWORDS DIAGNOSTICS, LINEAR SYSTEM, SLAP SPARSE
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C***AUTHOR Seager, Mark K., (LLNL)
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C Lawrence Livermore National Laboratory
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C PO BOX 808, L-60
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C Livermore, CA 94550 (510) 423-3141
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C seager@llnl.gov
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C***DESCRIPTION
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C
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C *Usage:
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C INTEGER N, NELT, IA(NELT), JA(NELT), ISYM, IUNIT, JOB
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C DOUBLE PRECISION A(NELT), SOLN(N), RHS(N)
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C
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C CALL DTIN( N, NELT, IA, JA, A, ISYM, SOLN, RHS, IUNIT, JOB )
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C
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C *Arguments:
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C N :OUT Integer
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C Order of the Matrix.
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C NELT :INOUT Integer.
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C On input NELT is the maximum number of non-zeros that
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C can be stored in the IA, JA, A arrays.
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C On output NELT is the number of non-zeros stored in A.
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C IA :OUT Integer IA(NELT).
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C JA :OUT Integer JA(NELT).
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C A :OUT Double Precision A(NELT).
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C On output these arrays hold the matrix A in the SLAP
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C Triad format. See "Description", below.
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C ISYM :OUT Integer.
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C Flag to indicate symmetric storage format.
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C If ISYM=0, all non-zero entries of the matrix are stored.
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C If ISYM=1, the matrix is symmetric, and only the lower
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C triangle of the matrix is stored.
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C SOLN :OUT Double Precision SOLN(N).
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C The solution to the linear system, if present. This array
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C is accessed if and only if JOB to read it in, see below.
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C If the user requests that SOLN be read in, but it is not in
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C the file, then it is simply zeroed out.
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C RHS :OUT Double Precision RHS(N).
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C The right hand side vector. This array is accessed if and
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C only if JOB is set to read it in, see below.
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C If the user requests that RHS be read in, but it is not in
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C the file, then it is simply zeroed out.
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C IUNIT :IN Integer.
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C Fortran logical I/O device unit number to write the matrix
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C to. This unit must be connected in a system dependent fashion
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C to a file or the console or you will get a nasty message
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C from the Fortran I/O libraries.
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C JOB :INOUT Integer.
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C Flag indicating what I/O operations to perform.
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C On input JOB indicates what Input operations to try to
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C perform.
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C JOB = 0 => Read only the matrix.
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C JOB = 1 => Read matrix and RHS (if present).
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C JOB = 2 => Read matrix and SOLN (if present).
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C JOB = 3 => Read matrix, RHS and SOLN (if present).
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C On output JOB indicates what operations were actually
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C performed.
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C JOB = 0 => Read in only the matrix.
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C JOB = 1 => Read in the matrix and RHS.
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C JOB = 2 => Read in the matrix and SOLN.
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C JOB = 3 => Read in the matrix, RHS and SOLN.
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C
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C *Description:
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C The format for the input is as follows. On the first line
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C are counters and flags: N, NELT, ISYM, IRHS, ISOLN. N, NELT
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C and ISYM are described above. IRHS is a flag indicating if
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C the RHS was written out (1 is yes, 0 is no). ISOLN is a
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C flag indicating if the SOLN was written out (1 is yes, 0 is
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C no). The format for the fist line is: 5i10. Then comes the
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C NELT Triad's IA(I), JA(I) and A(I), I = 1, NELT. The format
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C for these lines is : 1X,I5,1X,I5,1X,D16.7. Then comes
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C RHS(I), I = 1, N, if IRHS = 1. Then comes SOLN(I), I = 1,
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C N, if ISOLN = 1. The format for these lines is: 1X,D16.7.
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C
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C =================== S L A P Triad format ===================
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C This routine requires that the matrix A be stored in the
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C SLAP Triad format. In this format only the non-zeros are
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C stored. They may appear in *ANY* order. The user supplies
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C three arrays of length NELT, where NELT is the number of
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C non-zeros in the matrix: (IA(NELT), JA(NELT), A(NELT)). For
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C each non-zero the user puts the row and column index of that
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C matrix element in the IA and JA arrays. The value of the
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C non-zero matrix element is placed in the corresponding
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C location of the A array. This is an extremely easy data
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C structure to generate. On the other hand it is not too
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C efficient on vector computers for the iterative solution of
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C linear systems. Hence, SLAP changes this input data
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C structure to the SLAP Column format for the iteration (but
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C does not change it back).
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C
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C Here is an example of the SLAP Triad storage format for a
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C 5x5 Matrix. Recall that the entries may appear in any order.
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C
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C 5x5 Matrix SLAP Triad format for 5x5 matrix on left.
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C 1 2 3 4 5 6 7 8 9 10 11
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C |11 12 0 0 15| A: 51 12 11 33 15 53 55 22 35 44 21
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C |21 22 0 0 0| IA: 5 1 1 3 1 5 5 2 3 4 2
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C | 0 0 33 0 35| JA: 1 2 1 3 5 3 5 2 5 4 1
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C | 0 0 0 44 0|
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C |51 0 53 0 55|
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C
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C *Cautions:
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C This routine will attempt to write to the Fortran logical output
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C unit IUNIT, if IUNIT .ne. 0. Thus, the user must make sure that
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C this logical unit is attached to a file or terminal before calling
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C this routine with a non-zero value for IUNIT. This routine does
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C not check for the validity of a non-zero IUNIT unit number.
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C***REFERENCES (NONE)
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C***ROUTINES CALLED (NONE)
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C***REVISION HISTORY (YYMMDD)
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C 871119 DATE WRITTEN
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C 881213 Previous REVISION DATE
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C 890915 Made changes requested at July 1989 CML Meeting. (MKS)
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C 890922 Numerous changes to prologue to make closer to SLATEC
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C standard. (FNF)
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C 890929 Numerous changes to reduce SP/DP differences. (FNF)
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C 910411 Prologue converted to Version 4.0 format. (BAB)
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C 920511 Added complete declaration section. (WRB)
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C 921007 Changed E's to D's in formats. (FNF)
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C 930701 Updated CATEGORY section. (FNF, WRB)
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C***END PROLOGUE DTIN
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C .. Scalar Arguments ..
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INTEGER ISYM, IUNIT, JOB, N, NELT
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C .. Array Arguments ..
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DOUBLE PRECISION A(NELT), RHS(N), SOLN(N)
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INTEGER IA(NELT), JA(NELT)
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C .. Local Scalars ..
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INTEGER I, IRHS, ISOLN, JOBRET, NELTMX
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C .. Intrinsic Functions ..
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INTRINSIC MIN
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C***FIRST EXECUTABLE STATEMENT DTIN
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C
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C Read in the information heading.
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C
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NELTMX = NELT
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READ(IUNIT,1000) N, NELT, ISYM, IRHS, ISOLN
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NELT = MIN( NELT, NELTMX )
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C
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C Read in the matrix non-zeros in Triad format.
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DO 10 I = 1, NELT
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READ(IUNIT,1010) IA(I), JA(I), A(I)
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10 CONTINUE
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C
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C If requested, read in the rhs.
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JOBRET = 0
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IF( JOB.EQ.1 .OR. JOB.EQ.3 ) THEN
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C
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C Check to see if rhs is in the file.
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IF( IRHS.EQ.1 ) THEN
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JOBRET = 1
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READ(IUNIT,1020) (RHS(I),I=1,N)
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ELSE
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DO 20 I = 1, N
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RHS(I) = 0
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20 CONTINUE
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ENDIF
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ENDIF
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C
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C If requested, read in the solution.
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IF( JOB.GT.1 ) THEN
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C
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C Check to see if solution is in the file.
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IF( ISOLN.EQ.1 ) THEN
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JOBRET = JOBRET + 2
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READ(IUNIT,1020) (SOLN(I),I=1,N)
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ELSE
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DO 30 I = 1, N
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SOLN(I) = 0
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30 CONTINUE
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ENDIF
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ENDIF
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C
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JOB = JOBRET
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RETURN
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1000 FORMAT(5I10)
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1010 FORMAT(1X,I5,1X,I5,1X,D16.7)
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1020 FORMAT(1X,D16.7)
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C------------- LAST LINE OF DTIN FOLLOWS ----------------------------
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END
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