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