Re: Simplify problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg95805] Re: Simplify problem*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>*Date*: Wed, 28 Jan 2009 06:26:35 -0500 (EST)*Organization*: The Open University, Milton Keynes, UK*References*: <glmstk$mm3$1@smc.vnet.net>

In article <glmstk$mm3$1 at smc.vnet.net>, tidy512 at googlemail.com wrote: > I am using Simplify / FullSimplify etc. to simplify some equations > I have, but I am unable to coerce Mathematica into automatically > giving me the form I require for some of the sub-expressions, e.g. > > I'd like > > 1/Sqrt[1 + 1/x] > > to be automatically converted to > > Sqrt[x/(1 + x)] > > 'x' is always of type Real and greater-than 0 btw. > > I would appreciate any help or tips anyone can provide on this. Broadly speaking, Mathematica mainly uses *LeafCount* to assess the complexity of expressions. For instance, of two expressions, the one with the lowest value for *LeafCount* will be deemed as simpler than the other. In[2]:= 1/Sqrt[1 + 1/x] // LeafCount Out[2]= 9 In[3]:= Sqrt[x/(1 + x)] // LeafCount Out[3]= 11 So Simmplify/FullSimplify is not going to go from the first from to the second except if one can modify/write appropriately the complexity function used by FullSimplify. See http://reference.wolfram.com/mathematica/ref/ComplexityFunction.html Regards, --Jean-Marc