Re: About Simplify
- To: mathgroup at smc.vnet.net
- Subject: [mg59669] Re: About Simplify
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Wed, 17 Aug 2005 04:00:23 -0400 (EDT)
- References: <200508160939.FAA10679@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
It may be of some interest to note here that one can actually "take a
peak" at some of the transformations Mathematica uses in Simplify and
FullSimplify as follows:
ls = {};
FullSimplify[Cos[Arg[z]] - Re[z]/Abs[z], ComplexityFunction ->
((AppendTo[ls, #1]; LeafCount[#1]) & )]
0
Now evaluate
ls
Andrzej Kozlowski
On 16 Aug 2005, at 11:39, Peltio wrote:
> The recent threads about Simplify made me wonder why the user is
> not allowed
> to choose which transformation rules apply to the expression passed
> to it.
> Of course Simplify and FullSimplify are no longer (if they ever were)
> written in Mathematica code, but is it at all impossible to rewrite
> its
> interface in order to let the user interact with the builtin code?
>
> I do not know the way the code is structured for these procedures,
> but I can
> guess that at a certain point it will try to apply certain sets of
> rules
> having to do with trigonometric functions, Bessel functions,
> Hypergeometric
> functions and many other more or less exotic special functions.
> Is there no way at all to put switches to disable certain sets of
> rules?
> (A question for developers, of course - I do not think that
> Mathemaitca
> users can interact with the code).
>
> The user could pass a list of exclusion rules, such as
>
> Simplify[ expr, BesselFunctions->False, AiryFunctions->False,
> ErfFunctions->False]
>
> when the results he gets contain certain special functions he does
> not want
> to involve. The overhead for multiple switches will be minimal (the
> procedure will have to modify a table which will be looked up by the
> internal C code) and the user will be able to build custom simplify
> solutions (one that uses only algebraic and trigonometric
> functions, one
> that uses the orthogonal polynomials, one tht does not use
> hypergeometric
> functions and so on).
>
> I can imagine that the built-in code is not a sequence of
> transormation
> rules to apply in chain one after the other, but perhaps many special
> functions rules could be switched on and off at will without
> afffecting the
> remaining code.
> Or is it completely unthinkable?
>
> just wondering,
> Peltio
> Invalid address in reply-to. Crafty demunging required to mail me.
>
>
- References:
- About Simplify
- From: "Peltio" <peltio@trilight.zone>
- About Simplify