diff --git a/mono/EllipseAntialiasing/EllipseAntialiasing.csproj b/mono/EllipseAntialiasing/EllipseAntialiasing.csproj
new file mode 100644
index 0000000..1d4923f
--- /dev/null
+++ b/mono/EllipseAntialiasing/EllipseAntialiasing.csproj
@@ -0,0 +1,42 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">x86</Platform>
+    <ProductVersion>10.0.0</ProductVersion>
+    <SchemaVersion>2.0</SchemaVersion>
+    <ProjectGuid>{77CD6953-34F0-4125-9DF5-957ECF0E23F0}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <RootNamespace>EllipseAntialiasing</RootNamespace>
+    <AssemblyName>EllipseAntialiasing</AssemblyName>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x86' ">
+    <DebugSymbols>true</DebugSymbols>
+    <DebugType>full</DebugType>
+    <Optimize>false</Optimize>
+    <OutputPath>bin\Debug</OutputPath>
+    <DefineConstants>DEBUG;</DefineConstants>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <PlatformTarget>x86</PlatformTarget>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x86' ">
+    <DebugType>none</DebugType>
+    <Optimize>true</Optimize>
+    <OutputPath>bin\Release</OutputPath>
+    <ErrorReport>prompt</ErrorReport>
+    <WarningLevel>4</WarningLevel>
+    <PlatformTarget>x86</PlatformTarget>
+    <ConsolePause>false</ConsolePause>
+  </PropertyGroup>
+  <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
+  <ItemGroup>
+    <Compile Include="MainWindow.cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <Reference Include="System.Drawing" />
+    <Reference Include="System.Windows.Forms" />
+    <Reference Include="System" />
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/mono/EllipseAntialiasing/EllipseAntialiasing.sln b/mono/EllipseAntialiasing/EllipseAntialiasing.sln
new file mode 100644
index 0000000..804628b
--- /dev/null
+++ b/mono/EllipseAntialiasing/EllipseAntialiasing.sln
@@ -0,0 +1,20 @@
+
+Microsoft Visual Studio Solution File, Format Version 11.00
+# Visual Studio 2010
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "EllipseAntialiasing", "EllipseAntialiasing.csproj", "{77CD6953-34F0-4125-9DF5-957ECF0E23F0}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|x86 = Debug|x86
+		Release|x86 = Release|x86
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{77CD6953-34F0-4125-9DF5-957ECF0E23F0}.Debug|x86.ActiveCfg = Debug|x86
+		{77CD6953-34F0-4125-9DF5-957ECF0E23F0}.Debug|x86.Build.0 = Debug|x86
+		{77CD6953-34F0-4125-9DF5-957ECF0E23F0}.Release|x86.ActiveCfg = Release|x86
+		{77CD6953-34F0-4125-9DF5-957ECF0E23F0}.Release|x86.Build.0 = Release|x86
+	EndGlobalSection
+	GlobalSection(MonoDevelopProperties) = preSolution
+		StartupItem = EllipseAntialiasing.csproj
+	EndGlobalSection
+EndGlobal
diff --git a/mono/EllipseAntialiasing/MainWindow.cs b/mono/EllipseAntialiasing/MainWindow.cs
new file mode 100644
index 0000000..5ef348c
--- /dev/null
+++ b/mono/EllipseAntialiasing/MainWindow.cs
@@ -0,0 +1,134 @@
+using System;
+using System.Drawing;
+using System.Drawing.Imaging;
+using System.Windows.Forms;
+using System.Collections.Generic;
+
+namespace Faraday {
+    public class MainWindow : Form {
+        static public void Main() { Application.Run(new MainWindow()); }
+
+		double tangentLength = 1000.0;
+		double normalLength = 50.0;
+		double pointRadius = 4.0;
+
+		double targetX = 0.0;
+		double targetY = 0.0;
+
+		double aaRadius = 25.0;
+		double radiusX = 400.0;
+		double radiusY = 100.0;
+
+		public MainWindow() {
+            Paint += OnPaint;
+			MouseMove += OnMouseMove;
+            WindowState = FormWindowState.Maximized;
+        }
+
+        public void OnPaint(Object sender, PaintEventArgs e) {
+            Draw(e.Graphics);
+        }
+
+        public void OnMouseMove(Object sender, MouseEventArgs e) {
+			targetX = e.X - 0.5*ClientSize.Width;
+			targetY = e.Y - 0.5*ClientSize.Height;
+			Invalidate();
+        }
+
+        public void Draw(Graphics g) {
+            g.Clear(Color.White);
+			g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
+
+			double centerX = 0.5*ClientSize.Width;
+			double centerY = 0.5*ClientSize.Height;
+
+			g.DrawEllipse(
+				Pens.Gray,
+				(float)(centerX - radiusX),
+				(float)(centerY - radiusY),
+				(float)(2.0*radiusX),
+				(float)(2.0*radiusY));
+
+			g.FillEllipse(
+				Brushes.Blue,
+				(float)(centerX + targetX - pointRadius),
+				(float)(centerY + targetY - pointRadius),
+				(float)(2.0*pointRadius),
+				(float)(2.0*pointRadius));
+
+			if (Math.Abs(targetX) > 0.0 || Math.Abs(targetY) > 0.0) {
+				double targetL = Math.Sqrt(
+					targetY*targetY +
+					targetX*targetX);
+				double targetNormX = targetX/targetL;
+				double targetNormY = targetY/targetL;
+
+				g.DrawLine(
+					Pens.Black,
+					(float)centerX,
+					(float)centerY,
+					(float)(centerX + tangentLength*targetNormX),
+					(float)(centerY + tangentLength*targetNormY));
+
+				double crossL = Math.Sqrt(
+					targetY*targetY*radiusX*radiusX +
+					targetX*targetX*radiusY*radiusY);
+				double crossX = targetX*radiusX*radiusY/crossL;
+				double crossY = targetY*radiusX*radiusY/crossL;
+
+				g.FillEllipse(
+					Brushes.Blue,
+					(float)(centerX + crossX - pointRadius),
+					(float)(centerY + crossY - pointRadius),
+					(float)(2.0*pointRadius),
+					(float)(2.0*pointRadius));
+
+				double tangentL = Math.Sqrt(
+					targetY*targetY*radiusX*radiusX*radiusX*radiusX +
+					targetX*targetX*radiusY*radiusY*radiusY*radiusY);
+				double tangentX = targetY*radiusX*radiusX/tangentL;
+				double tangentY = -targetX*radiusY*radiusY/tangentL;
+
+				g.DrawLine(
+					Pens.Blue,
+					(float)(centerX + crossX - tangentX*tangentLength),
+					(float)(centerY + crossY - tangentY*tangentLength),
+					(float)(centerX + crossX + tangentX*tangentLength),
+					(float)(centerY + crossY + tangentY*tangentLength));
+
+				double normalX = -tangentY;
+				double normalY = tangentX;
+
+				g.DrawLine(
+					Pens.Blue,
+					(float)(centerX + crossX),
+					(float)(centerY + crossY),
+					(float)(centerX + crossX + normalX*normalLength),
+					(float)(centerY + crossY + normalY*normalLength));
+
+				double dot = normalX*targetNormX + normalY*targetNormY;
+				double aa = aaRadius/dot;
+
+				g.DrawLine(
+					Pens.Red,
+					(float)(centerX + targetX - targetNormX*aa),
+					(float)(centerY + targetY - targetNormY*aa),
+					(float)(centerX + targetX + targetNormX*aa),
+					(float)(centerY + targetY + targetNormY*aa));
+				g.FillEllipse(
+					Brushes.Red,
+					(float)(centerX + targetX - targetNormX*aa - pointRadius),
+					(float)(centerY + targetY - targetNormY*aa - pointRadius),
+					(float)(2.0*pointRadius),
+					(float)(2.0*pointRadius));
+				g.FillEllipse(
+					Brushes.Red,
+					(float)(centerX + targetX + targetNormX*aa - pointRadius),
+					(float)(centerY + targetY + targetNormY*aa - pointRadius),
+					(float)(2.0*pointRadius),
+					(float)(2.0*pointRadius));
+			}
+        }
+    }
+}
+