Re: computer algebra software

As Richard Fateman said, you may want to learn Scheme or Lisp to be able:
- to use very big exact numbers (integers and rationals p/q)
- to learn a masterpiece of programming :-) whose knowledge is
unvaluable to use other computer algebra software as Mathematica or
Maple...

For example, with a 3 lines function (exptmod a b n) which computes
a^b modulo n, and whose details are given in :
mitpress.mit.edu/sicp/full-text/book/book-Z-H-11.html#%25_sec_1.2.6
I get the following at the DrScheme prompt if I try to raise the number
12345678901236545432 to the power 65434598654321676543234554, working
modulo 59876654655677645. Yes, my old Mac laptop is so slow....

(time (exptmod 12345678901236545432 65434598654321676543234554 59876654655677645))
cpu time: 8 milliseconds
4088604362981014

DrScheme is a very nice environment for programming in Scheme !

JG



In article <A4yGf.10403$2O6.2589@xxxxxxxxxxxxxxxxxxxxxxxxxx>,
"Richard Fateman" <fateman@xxxxxxxxxxxxxxx> wrote:

"curiousblack" <ebhume@xxxxxxxxxxxx> wrote in message
news:6584801.1139435552809.JavaMail.jakarta@xxxxxxxxxxxxxxxxxxxxxxxxx
Does anyone know of any (preferably basic pgm language) downloadable
algorithms for exact calculations with very large integers - such as those
which lose precision in typical computer computation? I was hoping for
freeware, something I could experiment with on a PC....

try
http://www.rain.org/~mkummel/tbvault.html
and look for bignum.

You didn't ask, but I'll add that you would probably benefit from
downloading and learning
scheme or common lisp, each of which uses arbitrary precision integers as
a matter of course. It might also show you that there are rather different
languages than BASIC.

RJF
.

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