subroutine timer(dname,k)

! Times procedure number n between a call with k=0 (tstart) and with
! k=1 (tstop). Accumulates sums of these times in array ut (user time).
! Also traces all calls (for debugging purposes) if limtrace.gt.0

  character*8 dname,name(50),space,ename
  character*16 sname
  logical on(50)
  real ut(50),ut0(50),dut(50),tt(2)
  integer ncall(50),nlevel(50),nparent(50)
  integer onlevel(0:10)
  integer*8 count0,clkfreq
  common/tracer/ limtrace,lu
  data eps/0.000001/,ntrace/0/
  data level/0/,nmax/0/,space/'        '/
  data limtrace/0/,lu/-1/
  save

  if(limtrace.lt.0) go to 999
  if(lu.lt.1) lu=6
  if(k.gt.1) go to 40                        !Check for "all done" (k>1)
  onlevel(0)=0

  do n=1,nmax                                !Check for existing name
     if(name(n).eq.dname) go to 20
  enddo

  nmax=nmax+1                                !This is a new one
  n=nmax
  ncall(n)=0
  on(n)=.false.
  ut(n)=eps
  name(n)=dname

20 if(k.eq.0) then                                !Get start times (k=0)
     if(on(n)) print*,'Error in timer: ',dname,' already on.'
     level=level+1                                !Increment the level
     on(n)=.true.
     call system_clock(count0,clkfreq)
     ut0(n)=float(count0)/float(clkfreq)
     ncall(n)=ncall(n)+1
     if(ncall(n).gt.1.and.nlevel(n).ne.level) then
        nlevel(n)=-1
     else
        nlevel(n)=level
     endif
     nparent(n)=onlevel(level-1)
     onlevel(level)=n

  else if(k.eq.1) then        !Get stop times and accumulate sums. (k=1)
     if(on(n)) then
        on(n)=.false.
        call system_clock(count0,clkfreq)
        ut1=float(count0)/float(clkfreq)
        ut(n)=ut(n)+ut1-ut0(n)
     endif
     level=level-1
  endif

  ntrace=ntrace+1
  if(ntrace.lt.limtrace) write(lu,1020) ntrace,dname,k,level,nparent(n)
1020 format(i8,': ',a8,3i5)
  go to 998

! Write out the timer statistics

40 write(lu,1040)
1040 format(/'     name                 time  frac     dtime',       &
             ' dfrac  calls level parent'/75('-'))

  if(k.gt.100) then
     ndiv=k-100
     do i=1,nmax
        ncall(i)=ncall(i)/ndiv
        ut(i)=ut(i)/ndiv
     enddo
  endif

  total=ut(1)
  sum=0.
  sumf=0.
  do i=1,nmax
     dut(i)=ut(i)
     do j=i,nmax
        if(nparent(j).eq.i) dut(i)=dut(i)-ut(j)
     enddo
     utf=ut(i)/total
     dutf=dut(i)/total
     sum=sum+dut(i)
     sumf=sumf+dutf
     kk=min(nlevel(i),8)
     if(kk.lt.1) sname=name(i)//space
     if(kk.ge.1) sname=space(1:kk)//name(i)//space(1:8-kk)
     ename=space
     if(i.ge.2) ename=name(nparent(i))
     write(lu,1060) float(i),sname,ut(i),utf,dut(i),dutf,           &
          ncall(i),nlevel(i),ename
1060 format(f4.0,a16,2(f10.2,f6.2),i7,i5,2x,a8)
  enddo

  write(lu,1070) sum,sumf
1070 format(75('-')/36x,f10.2,f6.2)
  nmax=0
  eps=0.000001
  ntrace=0
  level=0
  space='        '
  onlevel(0)=0

998 flush(lu)

999 return
end subroutine timer