subroutine ssolsy (wm, iwm, x, tem)
!***BEGIN PROLOGUE  SSOLSY
!***SUBSIDIARY
!***PURPOSE  ODEPACK linear system solver.
!***TYPE      SINGLE PRECISION (SSOLSY-S, DSOLSY-D)
!***AUTHOR  Hindmarsh, Alan C., (LLNL)
!***DESCRIPTION
!
!  This routine manages the solution of the linear system arising from
!  a chord iteration.  It is called if MITER .ne. 0.
!  If MITER is 1 or 2, it calls SGESL to accomplish this.
!  If MITER = 3 it updates the coefficient h*EL0 in the diagonal
!  matrix, and then computes the solution.
!  If MITER is 4 or 5, it calls SGBSL.
!  Communication with SSOLSY uses the following variables:
!  WM    = real work space containing the inverse diagonal matrix if
!          MITER = 3 and the LU decomposition of the matrix otherwise.
!          Storage of matrix elements starts at WM(3).
!          WM also contains the following matrix-related data:
!          WM(1) = SQRT(UROUND) (not used here),
!          WM(2) = HL0, the previous value of h*EL0, used if MITER = 3.
!  IWM   = integer work space containing pivot information, starting at
!          IWM(21), if MITER is 1, 2, 4, or 5.  IWM also contains band
!          parameters ML = IWM(1) and MU = IWM(2) if MITER is 4 or 5.
!  X     = the right-hand side vector on input, and the solution vector
!          on output, of length N.
!  TEM   = vector of work space of length N, not used in this version.
!  IERSL = output flag (in COMMON).  IERSL = 0 if no trouble occurred.
!          IERSL = 1 if a singular matrix arose with MITER = 3.
!  This routine also uses the COMMON variables EL0, H, MITER, and N.
!
!***SEE ALSO  SLSODE
!***ROUTINES CALLED  SGBSL, SGESL
!***COMMON BLOCKS    SLS001
!***REVISION HISTORY  (YYMMDD)
!   791129  DATE WRITTEN
!   890501  Modified prologue to SLATEC/LDOC format.  (FNF)
!   890503  Minor cosmetic changes.  (FNF)
!   930809  Renamed to allow single/double precision versions. (ACH)
!   010412  Reduced size of Common block /SLS001/. (ACH)
!***END PROLOGUE  SSOLSY
!**End
      integer iwm
      integer icf, ierpj, iersl, jcur, jstart, kflag, l
      integer   lyh, lewt, lacor, lsavr, lwm, liwm, meth, miter
      integer   maxord, maxcor, msbp, mxncf, n, nq, nst, nfe, nje, nqu
      integer i, meband, ml, mu
      real wm, x, tem
      real ccmax, el0, h, hmin, hmxi, hu, rc, tn, uround
      real di, hl0, phl0, r
      dimension wm(*), iwm(*), x(*), tem(*)
      common /sls001/ ccmax, el0, h, hmin, hmxi, hu, rc, tn, uround,    &
     &   icf, ierpj, iersl, jcur, jstart, kflag, l,                     &
     &   lyh, lewt, lacor, lsavr, lwm, liwm, meth, miter,               &
     &   maxord, maxcor, msbp, mxncf, n, nq, nst, nfe, nje, nqu
!
!***first executable statement  ssolsy
      iersl = 0
      go to (100, 100, 300, 400, 400), miter
 100  call sgesl (wm(3), n, n, iwm(21), x, 0)
      return
!
 300  phl0 = wm(2)
      hl0 = h*el0
      wm(2) = hl0
      if (hl0 .eq. phl0) go to 330
      r = hl0/phl0
      do 320 i = 1,n
        di = 1.0e0 - r*(1.0e0 - 1.0e0/wm(i+2))
        if (abs(di) .eq. 0.0e0) go to 390
 320    wm(i+2) = 1.0e0/di
 330  do 340 i = 1,n
 340    x(i) = wm(i+2)*x(i)
      return
 390  iersl = 1
      return
!
 400  ml = iwm(1)
      mu = iwm(2)
      meband = 2*ml + mu + 1
      call sgbsl (wm(3), meband, n, ml, mu, iwm(21), x, 0)
      return
!----------------------- end of subroutine ssolsy ----------------------
      end