subroutine seterr (messg, nmessg, nerr, iopt)
c
c  this version modified by w. fullerton to dump if iopt = 1 and
c  not recovering.
c  seterr sets lerror = nerr, optionally prints the message and dumps
c  according to the following rules...
c
c    if iopt = 1 and recovering      - just remember the error.
c    if iopt = 1 and not recovering  - print, dump and stop.
c    if iopt = 2                     - print, dump and stop.
c
c  input
c
c    messg  - the error message.
c    nmessg - the length of the message, in characters.
c    nerr   - the error number. must have nerr non-zero.
c    iopt   - the option. must have iopt=1 or 2.
c
c  error states -
c
c    1 - message length not positive.
c    2 - cannot have nerr=0.
c    3 - an unrecovered error followed by another error.
c    4 - bad value for iopt.
c
c  only the first 72 characters of the message are printed.
c
c  the error handler calls a subroutine named fdump to produce a
c  symbolic dump. to complete the package, a dummy version of fdump
c  is supplied, but it should be replaced by a locally written version
c  which at least gives a trace-back.
c
      integer messg(1)
      external i1mach, i8save
c
c  the unit for error messages.
c
      iwunit=i1mach(4)
c
      if (nmessg.ge.1) go to 10
c
c  a message of non-positive length is fatal.
c
        write(iwunit,9000)
 9000   format(52h1error    1 in seterr - message length not positive.)
        go to 60
c
c  nw is the number of words the message occupies.
c
 10   nw=(min0(nmessg,72)-1)/i1mach(6)+1
c
      if (nerr.ne.0) go to 20
c
c  cannot turn the error state off using seterr.
c
        write(iwunit,9001)
 9001   format(42h1error    2 in seterr - cannot have nerr=0//
     1         34h the current error message follows///)
        call e9rint(messg,nw,nerr,.true.)
        itemp=i8save(1,1,.true.)
        go to 50
c
c  set lerror and test for a previous unrecovered error.
c
 20   if (i8save(1,nerr,.true.).eq.0) go to 30
c
        write(iwunit,9002)
 9002   format(23h1error    3 in seterr -,
     1         48h an unrecovered error followed by another error.//
     2         48h the previous and current error messages follow.///)
        call eprint
        call e9rint(messg,nw,nerr,.true.)
        go to 50
c
c  save this message in case it is not recovered from properly.
c
 30   call e9rint(messg,nw,nerr,.true.)
c
      if (iopt.eq.1 .or. iopt.eq.2) go to 40
c
c  must have iopt = 1 or 2.
c
        write(iwunit,9003)
 9003   format(42h1error    4 in seterr - bad value for iopt//
     1         34h the current error message follows///)
        go to 50
c
c  test for recovery.
c
 40   if (iopt.eq.2) go to 50
c
      if (i8save(2,0,.false.).eq.1) return
c
c     call eprint
c     stop
c
 50   call eprint
 60   call fdump
      stop
c
      end