pro FUNCT,X,A,F,PDER
common iter,titer
; INPUTS:
;	X = VALUES OF INDEPENDENT VARIABLE.
;	A = PARAMETERS OF EQUATION DESCRIBED BELOW.
; OUTPUTS:
;	F         = Value of function at each X(I).
;	PDER(I,J) = Derivative	at Ith point WRT Jth parameter.
nx = n_elements(x)
na = n_elements(a)
titer=-1
fun,x,a,f
if ( n_params(dummy) eq 4 ) then begin 
   pder = fltarr(nx,na)
   for ia = 0,na-1 do begin
      titer=ia
      anew = a
      anew(ia) = a(ia) * 1.001 + 0.001 * (a(ia) eq 0.)
      print,format='(i2,A,$)',ia ,'..'
      fnew=f
      fun,x,anew,fnew
      if(anew(ia) ne a(ia)) then pder(0,ia) = (fnew-f) / (anew(ia)-a(ia))
   endfor
   print,format='(A)','-'
endif
return
end