;
pro fminmax, f,n,rmin,rmax,spval
;
rmin = 1.e36
rmax = -1.e36
for i=0,n-1 do begin
  if (f(i) ne spval and f(i) gt rmax) then rmax = f(i)
  if (f(i) ne spval and f(i) lt rmin) then rmin = f(i)
endfor
return
end