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Re: General--Exponential simplifications by default

  • To: mathgroup at
  • Subject: [mg69008] Re: [mg68966] General--Exponential simplifications by default
  • From: Daniel Lichtblau <danl at>
  • Date: Sat, 26 Aug 2006 02:04:56 -0400 (EDT)
  • References: <>
  • Sender: owner-wri-mathgroup at

guillaume_evin at 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_, &#8734;] &)" 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:
> Posted through [[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]]]
-theta/(2*alpha*E^(2*eta*y)) + (2 + theta)/(2*alpha*E^(eta*y))

Daniel Lichtblau
Wolfram Research

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