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MathGroup Archive 2006

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Re: Integration (change of variable)

  • To: mathgroup at smc.vnet.net
  • Subject: [mg71755] Re: Integration (change of variable)
  • From: Peter Pein <petsie at dordos.net>
  • Date: Tue, 28 Nov 2006 06:04:10 -0500 (EST)
  • Organization: 1&1 Internet AG
  • References: <ekebgc$1a$1@smc.vnet.net>

KFUPM schrieb:
> Dear All
> 
> I have a function that to be integrated with respect to s , the
> function is :
> 
> (2*E^(((-Sqrt[p] - V)*x)/2)*γ*DifferentialD[(p - V^2)/4])/(-Sqrt[p] -
> V)
> 
> What i need to to do is actually change the varible s into p (before
> the integratio) according to the relation
> 
> p=4*s+V^2;
> 
> How can i automatically do that (changing the variable) using
> mathematica ? Remember that i have the term "ds" which i should take
> care of when i make the change .
> 
> Any help in this regard will be highly appreciated
> 
> Many thanks in advance
> 
> HMQ
> 

Hello,

let's call your expression expr. Then

expr /. {DifferentialD -> Dt, p -> 4*s + V^2} /. Dt -> DifferentialD

gives:

(2*E^((1/2)*(-V - Sqrt[4*s + V^2])*x)*\[Gamma]*DifferentialD[s])/(-V -
Sqrt[4*s + V^2])


HTH,
P²


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