On Fri, Sep 11, 2009 at 12:31 PM, ?iga Lenar?i? <ziga.lenarcic at gmail.com> wrote:
> What I noticed while doing this is - that maxima is lacking a very used CAS
> feature - 'simplify'. What Simplify[] in Mathematica does is - perform
> various expression transformations and return the 'simplest' result. Yes -
> 'simplest' is always debatable, however consider this:
> * computer time is more valuable than users - a computer program can afford
> to employ large number of transformations and compare their results, do a
> search for the best, while the user - even if knowledgeable, has to type
> many commands to get the result he wants. It's nicer to call a function and
> wait a second or two, than to manually type in transformations.....
> So I propose we implement a 'simplify' command into Maxima....
Various versions of such functions have been posted on this mailing
list over the years.
As you point out, the two big issues are the simplicity metric and
calculation time. For small expressions, the calculation time may be
only a second or two, but for large expressions the calculation time
quickly becomes prohibitive. It would be nice if we could somehow
time-limit subexpression calculations, but I don't think there is any
reliable way of doing that.
And of course many useful transformations will not be found anyway.
For instance, I don't know of any practical way to perform
"simplifications" like x^5-14*x^4+94*x^3-264*x^2+409*x-242 =>
(x+1)^4+(x-3)^5.
-s