scpplt.f
SUBROUTINE SCPPLT (N, NELT, IA, JA, A, ISYM, IUNIT)
C***BEGIN PROLOGUE SCPPLT
C***PURPOSE Printer Plot of SLAP Column Format Matrix.
C Routine to print out a SLAP Column format matrix in a
C "printer plot" graphical representation.
C***LIBRARY SLATEC (SLAP)
C***CATEGORY N1
C***TYPE SINGLE PRECISION (SCPPLT-S, DCPPLT-D)
C***KEYWORDS DIAGNOSTICS, LINEAR SYSTEM, 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
C REAL A(NELT)
C
C CALL SCPPLT( N, NELT, IA, JA, A, ISYM, IUNIT )
C
C *Arguments:
C N :IN Integer
C Order of the Matrix.
C If N.gt.MAXORD, only the leading MAXORD x MAXORD
C submatrix will be printed. (Currently MAXORD = 225.)
C NELT :IN Integer.
C Number of non-zeros stored in A.
C IA :IN Integer IA(NELT).
C JA :IN Integer JA(NELT).
C A :IN Real A(NELT).
C These arrays should hold the matrix A in the SLAP
C Column format. See "Description", below.
C ISYM :IN 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 IUNIT :IN Integer.
C Fortran logical I/O device unit number to write the matrix
C to. This unit must be connected in a system dependent fashion
C to a file or the console or you will get a nasty message
C from the Fortran I/O libraries.
C
C *Description:
C This routine prints out a SLAP Column format matrix to the
C Fortran logical I/O unit number IUNIT. The numbers them
C selves are not printed out, but rather a one character
C representation of the numbers. Elements of the matrix that
C are not represented in the (IA,JA,A) arrays are denoted by
C ' ' character (a blank). Elements of A that are *ZERO* (and
C hence should really not be stored) are denoted by a '0'
C character. Elements of A that are *POSITIVE* are denoted by
C 'D' if they are Diagonal elements and '#' if they are off
C Diagonal elements. Elements of A that are *NEGATIVE* are
C denoted by 'N' if they are Diagonal elements and '*' if
C they are off Diagonal elements.
C
C =================== S L A P Column format ==================
C
C This routine requires that the matrix A be stored in the
C SLAP Column format. In this format the non-zeros are stored
C counting down columns (except for the diagonal entry, which
C must appear first in each "column") and are stored in the
C real array A. In other words, for each column in the matrix
C put the diagonal entry in A. Then put in the other non-zero
C elements going down the column (except the diagonal) in
C order. The IA array holds the row index for each non-zero.
C The JA array holds the offsets into the IA, A arrays for the
C beginning of each column. That is, IA(JA(ICOL)),
C A(JA(ICOL)) points to the beginning of the ICOL-th column in
C IA and A. IA(JA(ICOL+1)-1), A(JA(ICOL+1)-1) points to the
C end of the ICOL-th column. Note that we always have
C JA(N+1) = NELT+1, where N is the number of columns in the
C matrix and NELT is the number of non-zeros in the matrix.
C
C Here is an example of the SLAP Column storage format for a
C 5x5 Matrix (in the A and IA arrays '|' denotes the end of a
C column):
C
C 5x5 Matrix SLAP Column 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: 11 21 51 | 22 12 | 33 53 | 44 | 55 15 35
C |21 22 0 0 0| IA: 1 2 5 | 2 1 | 3 5 | 4 | 5 1 3
C | 0 0 33 0 35| JA: 1 4 6 8 9 12
C | 0 0 0 44 0|
C |51 0 53 0 55|
C
C *Cautions:
C This routine will attempt to write to the Fortran logical output
C unit IUNIT, if IUNIT .ne. 0. Thus, the user must make sure that
C this logical unit is attached to a file or terminal before calling
C this routine with a non-zero value for IUNIT. This routine does
C not check for the validity of a non-zero IUNIT unit number.
C
C *Portability:
C This routine, as distributed, can generate lines up to 229
C characters long. Some Fortran systems have more restricted
C line lengths. Change parameter MAXORD and the large number
C in FORMAT 1010 to reduce this line length.
C
C***REFERENCES (NONE)
C***ROUTINES CALLED (NONE)
C***REVISION HISTORY (YYMMDD)
C 871119 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 920511 Added complete declaration section. (WRB)
C 921007 Replaced hard-wired 225 with parameter MAXORD. (FNF)
C 921021 Corrected syntax of CHARACTER declaration. (FNF)
C 930701 Updated CATEGORY section. (FNF, WRB)
C***END PROLOGUE SCPPLT