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MathGroup Archive 2004

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Re: Re: newbie question DSolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg52183] Re: [mg52161] Re: newbie question DSolve
  • From: "Pratik Desai" <pdesai1 at umbc.edu>
  • Date: Sun, 14 Nov 2004 04:30:22 -0500 (EST)
  • References: <cmppui$mll$1@smc.vnet.net> <200411130940.EAA00981@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Thank you peter,

Could you please tell me what  version of mathematica you are using. When I 
try to implement your suggestion it gives me a "tdep" error--The equation 
appears to involve variables to be solved in a an essentially non-algebraic 
way. I am using 5.0.0 and I have tried the equation in 4.0.0  also 
unsuccessfully.

Best regards,

Pratik Desai


----- Original Message ----- 
From: "Peter Valko" <p-valko at tamu.edu>
To: mathgroup at smc.vnet.net
Subject: [mg52183] [mg52161] Re: newbie question DSolve


> Let us use the values:
>
> d=1/2;
> L=1;
> yL=1;
>
> and denote the unknown y[d] by yd. Then
>
> Solve[ yd == (y[x]/. DSolve[{-y[x] + Derivative[2][y][x] 
> ==DiracDelta[d-x]*yd,
>              y[0] == 0, y[L]== yL}, y[x], x][[1]])/.x->d];
>
> %//InputForm
>
> {{yd -> (2*Sqrt[E])/(1 + 3*E)}}
>
> Regards
> Peter
>
>
>
>
> "Pratik Desai" <pdesai1 at umbc.edu> wrote in message 
> news:<cmppui$mll$1 at smc.vnet.net>...
>> Hello all
>>
>> I am trying to use DSolve to solve a ode with discontinuity in it (wave
>> equation with a viscous damper injected at a location d)
>>
>> This is what i am using
>>
>> DSolve[{y''[x]-lamda^2*y[x]==DiracDelta[x-d]*y[x],y[0]==0,y[L]==
>> =0},y[x],x]
>>
>> the problem I am facing is that
>>
>> y[x] on the right hand side (next the delta function) varies w.r.t to
>> the location
>>
>> y[x]==y[x]&& 0<=x<=d
>> y[x]==y[L-x]&&d<=x<=L
>>
>> I can solve the above equation without the y[x] coupled to the delta
>> function
>>
>> Please advise and thanks in advance,
>>
>>
>> Pratik Desai
>>
>>
>> ps: This is my third attempt at posting my query, I hope this time it
>> makes it to the list :)
> 


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