a proper ellipsoid

ellipsoid.rb

@@ -1,12 +1,10 @@
-# python who ate an elephant
-
-class Python
+class Ellipsoid
   attr_reader :columns, :rows
 
   def initialize radius
     @columns = @rows = radius * 2
     lower_half = (0...radius).map do |y|
-      x = Math.sqrt(radius**2 - y**2).round
+      x = Math.sqrt(1 - y**2/radius**2)
       right_half = "#{"\xff" * x}#{"\x00" * (radius - x)}"
       "#{right_half.reverse}#{right_half}"
     end.join

particle.rb

@@ -1,4 +1,4 @@
-require './python.rb'
+require './ellipsoid.rb'
 
 # One particle is basically a sprite, that moves itself by speed every tick along an angle.
 # It also has a concept of decay, in how quickly the particle dies. In this case, the draw
@@ -15,7 +15,7 @@ class Particle
     @decay = decay
     
     radius = (rand * 10).floor
-    @img = Gosu::Image.new(window, Python.new(radius), false)
+    @img = Gosu::Image.new(window, Ellipsoid.new(radius), false)
   end
   
   def update