Re: General--Exponential simplifications by default

*To*: mathgroup at smc.vnet.net*Subject*: [mg69039] Re: General--Exponential simplifications by default*From*: p-valko at tamu.edu*Date*: Sun, 27 Aug 2006 01:24:22 -0400 (EDT)*References*: <200608250935.FAA09304@smc.vnet.net><ecoqnr$3bb$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Daniel, Could you tell me why the contradiction?: In[14]:=Exp[-x]//InputForm Out[14]//InputForm=E^(-x) In[15]:=Numerator[Exp[-x]]//InputForm Out[15]//InputForm=1 Mathematica automatically turns it into Power[E, Times[-1, x]], but the user beleives that the exponent is in the numerator. What you see is not what you get! My favorite contradiction is the following: In[24]:=Numerator[1/Sqrt[2]]//InputForm Out[24]//InputForm=Sqrt[2] In[25]:=Denominator[1/Sqrt[2]]//InputForm Out[25]//InputForm=2 I think "Numerator" and "Denominator" should not be allowed to do whatever they want. Too much liberty here... Peter Daniel Lichtblau wrote: > guillaume_evin at yahoo.fr wrote: > > Hi ! > > > > I want to avoid simplifications when Mathematica integrates expressions with exponential terms. For example, I have : > > > > In[8]= Espcond[y_] = Integrate[x*Densx[x, y], {x, 0, Infinity}, Assumptions -> alpha > 0] > > Out[8]= E^(-2eta y)(-theta + E^(eta y)(2+theta))/(2alpha) > > > > I do not want to have a factorization by E^(-2eta y). More precisely I would like to have the following result: > > Out[8]= (-theta E^(-2eta y)+ E^(-eta y)(2+theta))/(2alpha) > > > > I guess there is a way to tackle this problem with "ComplexityFunction" and "Simplify", but I tried different things such as "ComplexityFunction -> (Count[{#1}, Exp_, ∞] &)" in the "Simplify" function but no change appears. > > > > Is someone could give me some tricks on how tu use the "ComplexityFunction" ? > > > > Thank you in advance. > > > > Guillaume > > > > Link to the forum page for this post: > > http://www.mathematica-users.org/webMathematica/wiki/wiki.jsp?pageName=Special:Forum_ViewTopic&pid=12974#p12974 > > Posted through http://www.mathematica-users.org [[postId=12974]] > > > Could Collect with respect to powers of the exponential. > > In[59]:= ee = E^(-2eta*y)*(-theta + E^(eta*y)(2+theta))/(2*alpha); > > In[60]:= InputForm[Collect[ee, Exp[eta*y]]] > Out[60]//InputForm= > -theta/(2*alpha*E^(2*eta*y)) + (2 + theta)/(2*alpha*E^(eta*y)) > > Daniel Lichtblau > Wolfram Research

**Follow-Ups**:**Re: Re: General--Exponential simplifications by default***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>

**References**:**General--Exponential simplifications by default***From:*guillaume_evin@yahoo.fr