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Re: Forcing Certain Algebraic Forms With FullSimplify

• To: mathgroup at smc.vnet.net
• Subject: [mg123193] Re: Forcing Certain Algebraic Forms With FullSimplify
• From: Alexei Boulbitch <Alexei.Boulbitch at iee.lu>
• Date: Sat, 26 Nov 2011 05:06:36 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Hi, Scott,

There is a package "Presentations" of David Park that enables one doing such things. There are several ways doing with the presentations of what you need. For example:



Needs["Presentations`Manipulations`"];

a b + g // FactorOut[a]



a (b + g/a)



Alexei





Hi,



I would like to have Mathematica generate an output for an equation

where a certain variable is isolated.



For instance, I have the equation "a*b+g". I would like "b" to not be

multiplied by anything in the result. Thus, I would prefer the form

"a(b+g/a)".



I have attempted to do this with FullSimplify and ComplexityFunction.

The complexity function (cf) evaluates the way I want it to, but for

some reason FullSimplify gives me the answer I don't want.



Sample code:



cf[e_] := 100 Count[e, Times[b, __], Infinity] + LeafCount[e] ;



cf[a b + g]

cf[a (b + g/a)]



FullSimplify[a b + g, ComplexityFunction -> cf]



Output:



105

9

a b + g



Any ideas?



Thank you,

Scott



Alexei BOULBITCH, Dr., habil.

IEE S.A.

ZAE Weiergewan,

11, rue Edmond Reuter,

L-5326 Contern, LUXEMBOURG



Office phone :  +352-2454-2566

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e-mail: alexei.boulbitch at iee.lu<mailto:alexei.boulbitch at iee.lu>