=begin
= Ruby/PGPLOT example: pghist

=== code

  require 'narray'
  require 'pgplot'
  include Pgplot

  pgopen
  srand(1)

  # draw main Histogram of Normal distribution
  data = NArray.sfloat(1000).randomn!
  pghist(data, 31, -3.1..3.1, 0)

  # draw sub Histogram of Normal distribution with gray bars
  data = NArray.sfloat(200).randomn!*0.5 + 1 
  pgsci(15)
  pghist(data, 31, -3.1..3.1, 3)
  pgsci(0)  # draw black frame
  pghist(data, 31, -3.1..3.1, 1)

  pgsci(1)
  pgbox('BST', 0.0, 0, ' ', 0.0, 0)
  pglab('Variate', ' ','PGPLOT Example 4:  Histograms (Gaussian)')

  # draw Gaussian Curve
  x = NArray.sfloat(620).indgen!*0.01 - 3.1
  y = NMath.exp(-(x**2)*0.5) * (0.2*1000/NMath.sqrt(2*Math::PI))
  pgline(x,y)

=== output

<<< pghist.png

<<< trailer
=end