This version of Bracmat is the oldest version I have. It dates from 1986 and
is written for the Amstrad CPC464 in Locomotive Basic.

The program is called "FORMAT", because the program formats the input and
produces normalised output. Back in 1986 I did not realise that "to format" is
something you normally don't want to do. My computer's external memory was an
audio tape and needed no formatting before using it.

The program FORMAT.BAS is commented in German. I wanted to distribute the
program among other CPC464 users as freeware, and to that end you normally
sent your code with lots of comments to a magazine dedicated to your type of
machine. I don't remember the magazine's name. It was a German magazine and
they did not publish my excellent program.

This program is very educative. It exposes every step in the normalisation
process on the screen. All expressions are printed as trees, and as the
expression is painted onto the screen, sound is produced that indicates the
depth of the node currently being painted.

I used this program to compute the curvature R from a given metric. If you
have no idea of what General Relativity is about: computing R from a metric
involves many, many computations, each of which is easy, involving adding,
substraction, multiplying, division, exponentiation, taking the logarithm and
differentiation. The computation is very error-prone if done by hand.

The Basic version of Bracmat could only handle mathematical expressions. It
had no control structures and aggregate data types, so for that purpose I used
a Basic script that kept track of the matrices and the order in which to
produce them.

You can run the program on a CPC464, but an easier option is running it
from an emulator. I have used cpcemu-dos-x86-1.5
 

Good luck!

Bart Jongejan, 21 December 2009