Mar 062013

Analog computing in the dark!

I got interested in analog computers over the summer and ended up buying a Comdyna GP-6 off of eBay. They still make the GP-10 version and the Comdyna finds application in teaching labs and in control systems engineering. You can read about the history of the Comdyna GP-6 here.

The unit works and as a first computation I patched it up to simulate the Lorenz system.

The Lorenz system of ODEs is given by:

\frac{dx}{dt} = s (y-x)

\frac{dy}{dt} = r x-y-x z

\frac{dz}{dt} = x y - b z

The classic Lorenz butterfly results when s=10, r=28, and b=8/3.
Here’s the resulting program:

The “program” on the Comdyna GP-6.

And here are a few time-exposures of the program output.

The x-z plane of the phase space.

Another view of the x-z plane.

The x-y plane.


 Posted by at 6:01 PM
Jan 222011

After a few minutes of searching around, I found a quick way to get LaTeX onto this blog. Although, it seems like WordPress is the way to go if I want to get serious.

Here’s a preview: $P_{hover} = \sqrt{\frac{T^3}{2 \rho A}}$

Crap! That script uses MathML and that doesn’t work with Safari. Back to the drawing board.

 Posted by at 7:00 PM