SUBROUTINE S7RTDT(N,NNZ,INDROW,INDCOL,JPNTR,IWA)
      INTEGER N,NNZ
      INTEGER INDROW(NNZ),INDCOL(NNZ),JPNTR(1),IWA(N)
C     **********
C
C     SUBROUTINE S7RTDT
C
C     GIVEN THE NON-ZERO ELEMENTS OF AN M BY N MATRIX A IN
C     ARBITRARY ORDER AS SPECIFIED BY THEIR ROW AND COLUMN
C     INDICES, THIS SUBROUTINE PERMUTES THESE ELEMENTS SO
C     THAT THEIR COLUMN INDICES ARE IN NON-DECREASING ORDER.
C
C     ON INPUT IT IS ASSUMED THAT THE ELEMENTS ARE SPECIFIED IN
C
C           INDROW(K),INDCOL(K), K = 1,...,NNZ.
C
C     ON OUTPUT THE ELEMENTS ARE PERMUTED SO THAT INDCOL IS
C     IN NON-DECREASING ORDER. IN ADDITION, THE ARRAY JPNTR
C     IS SET SO THAT THE ROW INDICES FOR COLUMN J ARE
C
C           INDROW(K), K = JPNTR(J),...,JPNTR(J+1)-1.
C
C     NOTE THAT THE VALUE OF M IS NOT NEEDED BY S7RTDT AND IS
C     THEREFORE NOT PRESENT IN THE SUBROUTINE STATEMENT.
C
C     THE SUBROUTINE STATEMENT IS
C
C       SUBROUTINE S7RTDT(N,NNZ,INDROW,INDCOL,JPNTR,IWA)
C
C     WHERE
C
C       N IS A POSITIVE INTEGER INPUT VARIABLE SET TO THE NUMBER
C         OF COLUMNS OF A.
C
C       NNZ IS A POSITIVE INTEGER INPUT VARIABLE SET TO THE NUMBER
C         OF NON-ZERO ELEMENTS OF A.
C
C       INDROW IS AN INTEGER ARRAY OF LENGTH NNZ. ON INPUT INDROW
C         MUST CONTAIN THE ROW INDICES OF THE NON-ZERO ELEMENTS OF A.
C         ON OUTPUT INDROW IS PERMUTED SO THAT THE CORRESPONDING
C         COLUMN INDICES OF INDCOL ARE IN NON-DECREASING ORDER.
C
C       INDCOL IS AN INTEGER ARRAY OF LENGTH NNZ. ON INPUT INDCOL
C         MUST CONTAIN THE COLUMN INDICES OF THE NON-ZERO ELEMENTS
C         OF A. ON OUTPUT INDCOL IS PERMUTED SO THAT THESE INDICES
C         ARE IN NON-DECREASING ORDER.
C
C       JPNTR IS AN INTEGER OUTPUT ARRAY OF LENGTH N + 1 WHICH
C         SPECIFIES THE LOCATIONS OF THE ROW INDICES IN THE OUTPUT
C         INDROW. THE ROW INDICES FOR COLUMN J ARE
C
C               INDROW(K), K = JPNTR(J),...,JPNTR(J+1)-1.
C
C         NOTE THAT JPNTR(1) IS SET TO 1 AND THAT JPNTR(N+1)-1
C         IS THEN NNZ.
C
C       IWA IS AN INTEGER WORK ARRAY OF LENGTH N.
C
C     SUBPROGRAMS CALLED
C
C       FORTRAN-SUPPLIED ... MAX0
C
C     ARGONNE NATIONAL LABORATORY. MINPACK PROJECT. JUNE 1982.
C     THOMAS F. COLEMAN, BURTON S. GARBOW, JORGE J. MORE
C
C     **********
      INTEGER I,J,K,L
C
C     DETERMINE THE NUMBER OF NON-ZEROES IN THE COLUMNS.
C
      DO 10 J = 1, N
         IWA(J) = 0
   10    CONTINUE
      DO 20 K = 1, NNZ
         J = INDCOL(K)
         IWA(J) = IWA(J) + 1
   20    CONTINUE
C
C     SET POINTERS TO THE START OF THE COLUMNS IN INDROW.
C
      JPNTR(1) = 1
      DO 30 J = 1, N
         JPNTR(J+1) = JPNTR(J) + IWA(J)
         IWA(J) = JPNTR(J)
   30    CONTINUE
      K = 1
C
C     BEGIN IN-PLACE SORT.
C
   40 CONTINUE
         J = INDCOL(K)
         IF (K .LT. JPNTR(J) .OR. K .GE. JPNTR(J+1)) GO TO 50
C
C           CURRENT ELEMENT IS IN POSITION. NOW EXAMINE THE
C           NEXT ELEMENT OR THE FIRST UN-SORTED ELEMENT IN
C           THE J-TH GROUP.
C
            K = MAX0(K+1,IWA(J))
            GO TO 60
   50    CONTINUE
C
C           CURRENT ELEMENT IS NOT IN POSITION. PLACE ELEMENT
C           IN POSITION AND MAKE THE DISPLACED ELEMENT THE
C           CURRENT ELEMENT.
C
            L = IWA(J)
            IWA(J) = IWA(J) + 1
            I = INDROW(K)
            INDROW(K) = INDROW(L)
            INDCOL(K) = INDCOL(L)
            INDROW(L) = I
            INDCOL(L) = J
   60    CONTINUE
         IF (K .LE. NNZ) GO TO 40
      RETURN
C
C     LAST CARD OF SUBROUTINE S7RTDT.
C
      END

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