Carl's personal website - May the Source be with you

Thanks for visiting my site - I'll try to make it worth your while.  Below are some small programs that I've written, mostly to demonstrate sundry applications of mathematics and physics.  I've tried to provide variety but, as you'll see, I'm primarily a software guy and I'm not an authority on any of these topics.  Usually I gain most of my knowledge about a subject while researching it for my demonstration.  Full source code is included.

For something light, download the Earth Orbit demo, try the birthday trick or play Reversi.  For hardcore geeks, the best I can offer is BigInt, RSA with BigInts, or the Newtonian Gravity demo.  The Mandelbrot set viewer is light if you just admire the fractals, a bit heavier if you admire the underlying complex numbers.

My pièce de résistance is SpinShuffle, a unique new puzzle that is now available in free trial download form. If you like puzzles, I highly recommend checking it out at

Games and amusements

LiveMaze - got something to show the world?  Amaze them with this 3D showcase.  Another Carl exclusive.
Reversi - is this the most implemented game in the history of computing?  Play against your browser or view the source code.


Newtonian gravity  - a 3D environment for creating astronomical scenarios that demonstrate Newton's laws of gravity. 
Hohmann transfer orbits - well, it's not exactly rocket science but it... no, wait!  This IS rocket science!  Using the Newtonian gravity application, find out how to cut your fuel bill on your next trip to Mars.
Earth orbit demo - What causes Earth's seasons?  What are the tropics?  What is the Arctic Circle?  Fly around the solar system and find out with this funky C++/DirectX program.
BigInt - multiprecision integers - for those times when 18,446,744,073,709,551,616 just isn't enough... a C# datatype for big integers. And what has this got to do with The Simpsons?
RSA encryption with small numbers - it won't keep your password safe, but this demo will show you the RSA key-creation and encryption processes in action.
RSA with BigInts - still want more?  RSA and BigInts combined.
Mandelbrot set viewer - mind blowin', man...
The Four Fours puzzle - you'll sleep a little easier after this C# program shows you how to express 73, 79, 87 and more using exactly four fours.
The birthday trick - is it really true that in a group of 48 people there is a 95% chance that two have the same birthday?  Your computer doesn't lie...


Smiert Spionam - Fool spyware by typing your password using only the mouse.
Toolkit  - I have several handy utilities: the Base64 encoder/decoder; the .NET Regular Expression tester; the Javascript Regular Expression tester; and String Literalizer.


Portfolio - keep track of the state of your fortune with some easy-to-use ASP.NET 2.0 controls.
DateTimeListPicker - don't like calendar controls?  Try this alternative: a .NET 2.0 web user control for selecting dates and times using drop-down lists.
Articles - some modest insights into various aspects of software development (for more, see here)

©2012 Carl Johansen