SLATEC Routines --- DBHIN ---
*DECK DBHIN
SUBROUTINE DBHIN (N, NELT, IA, JA, A, ISYM, SOLN, RHS, IUNIT, JOB)
C***BEGIN PROLOGUE DBHIN
C***PURPOSE Read a Sparse Linear System in the Boeing/Harwell Format.
C The matrix is read in and if the right hand side is also
C present in the input file then it too is read in. The
C matrix is then modified to be in the SLAP Column format.
C***LIBRARY SLATEC (SLAP)
C***CATEGORY N1
C***TYPE DOUBLE PRECISION (SBHIN-S, DBHIN-D)
C***KEYWORDS LINEAR SYSTEM, MATRIX READ, SLAP SPARSE
C***AUTHOR Seager, Mark K., (LLNL)
C Lawrence Livermore National Laboratory
C PO BOX 808, L-60
C Livermore, CA 94550 (510) 423-3141
C seager@llnl.gov
C***DESCRIPTION
C
C *Usage:
C INTEGER N, NELT, IA(NELT), JA(NELT), ISYM, IUNIT, JOB
C DOUBLE PRECISION A(NELT), SOLN(N), RHS(N)
C
C CALL DBHIN( N, NELT, IA, JA, A, ISYM, SOLN, RHS, IUNIT, JOB )
C
C *Arguments:
C N :OUT Integer
C Order of the Matrix.
C NELT :INOUT Integer.
C On input NELT is the maximum number of non-zeros that
C can be stored in the IA, JA, A arrays.
C On output NELT is the number of non-zeros stored in A.
C IA :OUT Integer IA(NELT).
C JA :OUT Integer JA(NELT).
C A :OUT Double Precision A(NELT).
C On output these arrays hold the matrix A in the SLAP
C Triad format. See "Description", below.
C ISYM :OUT Integer.
C Flag to indicate symmetric storage format.
C If ISYM=0, all non-zero entries of the matrix are stored.
C If ISYM=1, the matrix is symmetric, and only the lower
C triangle of the matrix is stored.
C SOLN :OUT Double Precision SOLN(N).
C The solution to the linear system, if present. This array
C is accessed if and only if JOB is set to read it in, see
C below. If the user requests that SOLN be read in, but it is
C not in the file, then it is simply zeroed out.
C RHS :OUT Double Precision RHS(N).
C The right hand side vector. This array is accessed if and
C only if JOB is set to read it in, see below.
C If the user requests that RHS be read in, but it is not in
C the file, then it is simply zeroed out.
C IUNIT :IN Integer.
C Fortran logical I/O device unit number to read the matrix
C from. This unit must be connected in a system dependent
C fashion to a file, or you will get a nasty message
C from the Fortran I/O libraries.
C JOB :INOUT Integer.
C Flag indicating what I/O operations to perform.
C On input JOB indicates what Input operations to try to
C perform.
C JOB = 0 => Read only the matrix.
C JOB = 1 => Read matrix and RHS (if present).
C JOB = 2 => Read matrix and SOLN (if present).
C JOB = 3 => Read matrix, RHS and SOLN (if present).
C On output JOB indicates what operations were actually
C performed.
C JOB = -3 => Unable to parse matrix "CODE" from input file
C to determine if only the lower triangle of matrix
C is stored.
C JOB = -2 => Number of non-zeros (NELT) too large.
C JOB = -1 => System size (N) too large.
C JOB = 0 => Read in only the matrix.
C JOB = 1 => Read in the matrix and RHS.
C JOB = 2 => Read in the matrix and SOLN.
C JOB = 3 => Read in the matrix, RHS and SOLN.
C JOB = 10 => Read in only the matrix *STRUCTURE*, but no
C non-zero entries. Hence, A(*) is not referenced
C and has the return values the same as the input.
C JOB = 11 => Read in the matrix *STRUCTURE* and RHS.
C JOB = 12 => Read in the matrix *STRUCTURE* and SOLN.
C JOB = 13 => Read in the matrix *STRUCTURE*, RHS and SOLN.
C
C *Description:
C The format for the input is as follows. The first line contains
C a title to identify the data file. On the second line (5I4) are
C counters: NLINE, NPLS, NRILS, NNVLS, NRHSLS.
C NLINE Number of data lines (after the header) in the file.
C NPLS Number of lines for the Column Pointer data in the file.
C NRILS Number of lines for the Row indices in the file.
C NNVLS Number of lines for the Matrix elements in the file.
C NRHSLS Number of lines for the RHS in the file.
C The third line (A3,11X,4I4) contains a symmetry code and some
C additional counters: CODE, NROW, NCOL, NIND, NELE.
C On the fourth line (2A16,2A20) are formats to be used to read
C the following data: PNTFNT, RINFMT, NVLFMT, RHSFMT.
C Following that are the blocks of data in the order indicated.
C
C =================== S L A P Triad format ===================
C This routine requires that the matrix A be stored in the
C SLAP Triad format. In this format only the non-zeros are
C stored. They may appear in *ANY* order. The user supplies
C three arrays of length NELT, where NELT is the number of
C non-zeros in the matrix: (IA(NELT), JA(NELT), A(NELT)). For
C each non-zero the user puts the row and column index of that
C matrix element in the IA and JA arrays. The value of the
C non-zero matrix element is placed in the corresponding
C location of the A array. This is an extremely easy data
C structure to generate. On the other hand it is not too
C efficient on vector computers for the iterative solution of
C linear systems. Hence, SLAP changes this input data
C structure to the SLAP Column format for the iteration (but
C does not change it back).
C
C Here is an example of the SLAP Triad storage format for a
C 5x5 Matrix. Recall that the entries may appear in any order.
C
C 5x5 Matrix SLAP Triad format for 5x5 matrix on left.
C 1 2 3 4 5 6 7 8 9 10 11
C |11 12 0 0 15| A: 51 12 11 33 15 53 55 22 35 44 21
C |21 22 0 0 0| IA: 5 1 1 3 1 5 5 2 3 4 2
C | 0 0 33 0 35| JA: 1 2 1 3 5 3 5 2 5 4 1
C | 0 0 0 44 0|
C |51 0 53 0 55|
C
C *Portability:
C You must make sure that IUNIT is a valid Fortran logical
C I/O device unit number and that the unit number has been
C associated with a file or the console. This is a system
C dependent function.
C
C *Implementation note:
C SOLN is not read by this version. It will simply be
C zeroed out if JOB = 2 or 3 and the returned value of
C JOB will indicate SOLN has not been read.
C***REFERENCES (NONE)
C***ROUTINES CALLED (NONE)
C***REVISION HISTORY (YYMMDD)
C 881107 DATE WRITTEN
C 881213 Previous REVISION DATE
C 890915 Made changes requested at July 1989 CML Meeting. (MKS)
C 890922 Numerous changes to prologue to make closer to SLATEC
C standard. (FNF)
C 890929 Numerous changes to reduce SP/DP differences. (FNF)
C 910411 Prologue converted to Version 4.0 format. (BAB)
C 911122 Added loop to zero out RHS if user wants to read RHS, but
C it's not in the input file. (MKS)
C 911125 Minor improvements to prologue. (FNF)
C 920511 Added complete declaration section. (WRB)
C 921007 Corrected description of input format. (FNF)
C 921208 Added Implementation Note and code to zero out SOLN. (FNF)
C 930701 Updated CATEGORY section. (FNF, WRB)
C***END PROLOGUE DBHIN