share/odepack/fortran/mdm.f

   1       subroutine mdm
   2      *     (vk,tail, v,l, last,next, mark)
   3 c***********************************************************************
   4 c  mdm -- form element from uneliminated neighbors of vk
   5 c***********************************************************************
   6       integer  vk, tail,  v(*), l(*),   last(*), next(*),   mark(*),
   7      *   tag, s,ls,vs,es, b,lb,vb, blp,blpmax
   8       equivalence  (vs, es)
   9 c
  10 c----initialize tag and list of uneliminated neighbors
  11       tag = mark(vk)
  12       tail = vk
  13 c
  14 c----for each vertex/element vs/es in element list of vk
  15       ls = l(vk)
  16    1  s = ls
  17       if (s.eq.0)  go to 5
  18         ls = l(s)
  19         vs = v(s)
  20         if (next(vs).lt.0)  go to 2
  21 c
  22 c------if vs is uneliminated vertex, then tag and append to list of
  23 c------uneliminated neighbors
  24           mark(vs) = tag
  25           l(tail) = s
  26           tail = s
  27           go to 4
  28 c
  29 c------if es is active element, then ...
  30 c--------for each vertex vb in boundary list of element es
  31    2      lb = l(es)
  32           blpmax = last(es)
  33           do 3 blp=1,blpmax
  34             b = lb
  35             lb = l(b)
  36             vb = v(b)
  37 c
  38 c----------if vb is untagged vertex, then tag and append to list of
  39 c----------uneliminated neighbors
  40             if (mark(vb).ge.tag)  go to 3
  41               mark(vb) = tag
  42               l(tail) = b
  43               tail = b
  44    3        continue
  45 c
  46 c--------mark es inactive
  47           mark(es) = tag
  48 c
  49    4    go to 1
  50 c
  51 c----terminate list of uneliminated neighbors
  52    5  l(tail) = 0
  53 c
  54       return
  55       end