On Fri, 26 Nov 1999, Jerzy Karczmarczuk wrote:
> Do you know what makes Maple so attractive for newbies, for teachers,
> etc? One of the reasons is simply scandalous, awful, unbelievably
> silly : the lack of distinction between a symbolic indeterminate,
> and the program variable. You write ... f(x) ... and if x has not
> been previously assigned, you get 'x'. Computer algebra packages are
> - from the programming discipline perspective - monsters. You won't
> try to do things like that, in Haskell, ML, or anything reasonable.
The other problem with trying to implement a computer algebra library in
haskell (as opposed to writing a CA system in haskell) is that you need
the ability to scrutinise the `intermediate expressions' for
possible pattern matchinig rather than just the ultimate value. (Eg
sqr x = x*x
log (sqr x) = 2*log x
log x = PrimLog x
would still be valid even if hugs were modified so that sub-expressions
applying functions to indeterminates stopped the evaluation process once
an attempt was made to evaluate that subexpression and returned a `human
readable expression'. Modifying haskell to do this would slow `non
intermediate-expression matching' functional programs down so much (I
suspect) that I'm inclined to say that Haskell isn't suitable for doing
computer algebra natively, and that this is a reasonable design decision.
I'm much more hopeful that functional programming languages will be useful
for prototyping numerical/scientific applications (is that what you mean
when you say scripting Eduardo?).
(I'm currently setting aside the first morning of my christmas break to
try and make comprehensible to someone other than me the numerically
intense algorithms in C vs Haskell that I mentioned ages ago on a thread
entitled "Cryptarithm test" (I think). Urgent need to get my Phd stuff
working has unfortunately prevented me from doing this so far.)
___cheers,_dave________________________________________________________
www.cs.bris.ac.uk/~tweed/pi.htm Farenheit 451 is the temperature at
email: [EMAIL PROTECTED] which paper burns. Let's do an experiment to
work tel: (0117) 954-5253 see what temperature melts human brain cells.
