share/odepack/fortran/cntnzu.f

   1 *DECK CNTNZU
   2       SUBROUTINE CNTNZU (N, IA, JA, NZSUT)
   3       INTEGER N, IA, JA, NZSUT
   4       DIMENSION IA(*), JA(*)
   5 C-----------------------------------------------------------------------
   6 C This routine counts the number of nonzero elements in the strict
   7 C upper triangle of the matrix M + M(transpose), where the sparsity
   8 C structure of M is given by pointer arrays IA and JA.
   9 C This is needed to compute the storage requirements for the
  10 C sparse matrix reordering operation in ODRV.
  11 C-----------------------------------------------------------------------
  12       INTEGER II, JJ, J, JMIN, JMAX, K, KMIN, KMAX, NUM
  13 C
  14       NUM = 0
  15       DO 50 II = 1,N
  16         JMIN = IA(II)
  17         JMAX = IA(II+1) - 1
  18         IF (JMIN .GT. JMAX) GO TO 50
  19         DO 40 J = JMIN,JMAX
  20           IF (JA(J) - II) 10, 40, 30
  21  10       JJ =JA(J)
  22           KMIN = IA(JJ)
  23           KMAX = IA(JJ+1) - 1
  24           IF (KMIN .GT. KMAX) GO TO 30
  25           DO 20 K = KMIN,KMAX
  26             IF (JA(K) .EQ. II) GO TO 40
  27  20         CONTINUE
  28  30       NUM = NUM + 1
  29  40       CONTINUE
  30  50     CONTINUE
  31       NZSUT = NUM
  32       RETURN
  33 C----------------------- End of Subroutine CNTNZU ----------------------
  34       END