Re: question

*To*: mathgroup at smc.vnet.net*Subject*: [mg74925] Re: question*From*: "Michael Weyrauch" <michael.weyrauch at gmx.de>*Date*: Wed, 11 Apr 2007 02:01:43 -0400 (EDT)*References*: <evd3ku$5dd$1@smc.vnet.net>

Hello, well, I think your command > In[57]:= > FullSimplify[Log[x+1],ComplexityFunction\[Rule] > (Count[{#1},_Log,Infinity]&)] > fails, because Log[z] as implemented in Mathematica does not know the transformation rules back into Hypergeometric functions. If I do it as follows under Mathematica 5.2 it works without problems... Unprotect[Log]; Simplify[Log[x + 1], ComplexityFunction -> (Count[{#1}, _Log, Infinity] & ), TransformationFunctions -> {Log[z_] := Hypergeometric2F1[1, 1, 2, -z + 1]* (z - 1)}] (*output*) x*Hypergeometric2F1[1, 1, 2, -x] Of course, I have to use Unprotect, since I am adding a rule to an internal command. So, if for some reason I would like to "simplify" e.g. Log[x+1]^2 it works as exspected Simplify[Log[x + 1]^2, ComplexityFunction -> (Count[{#1}, _Log, Infinity] & ), TransformationFunctions -> {Log[z_] := Hypergeometric2F1[1, 1, 2, -z + 1]* (z - 1)}] (*output*) x^2*Hypergeometric2F1[1, 1, 2, -x]^2 Therefore, I am not sure, if Andrzej Kozlowski is right here? Regards Michael

**Follow-Ups**:**Re: Re: question***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>