;---Generate some random data.
  x = tointeger(random_uniform(0,33,150))
  y = tointeger(random_uniform(0,33,150))

  wks = gsn_open_wks("x11","histo")        ; Open workstation 

  res = True 

  res@gsnMaximize                     = True    ; Maximize plot in frame.

  res@gsnHistogramSelectNiceIntervals = False
  res@gsnHistogramNumberOfBins        = 6

  res@tmXBLabels = (/"","one","two","three","four","five",""/)   ; there are 6 bins; hence 7 tickmarks

  res@trXMinF                         = -0.03    ; This adds a little bit of margin to the
  res@trXMaxF                         =  1.03    ; begin and end of X axis.

  plot = gsn_histogram(wks,x,res)
 
  values = fspan(0,1,7)
  res@tmXBValues = values(1:5)
  res@tmXBLabels := sprintf("%3.1f",values(1:5))
  plot = gsn_histogram(wks,x,res)