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Re: differential equation with buondary conditions


Would 

DSolve[{y''[x] + k y[x] == 0,y[0]==0}, y[x], x]



do what you want ?



Pete





----- Original Message ----- 
From: "Gustavo Seabra" <gseabra at swbell.net>
To: mathgroup at smc.vnet.net
Subject: [mg30319] [mg30313] differential equation with buondary conditions


> Hello,
> 
>     I'm trying to make Mathematica solve the following:
> 
>                             y''[x] + k y[x] == 0
> 
> subject to the boundary conditions:
>         y[x<0] = 0
>         y[x>a] = 0
> so that y[x] != 0 only if 0 < x < a.
> (yes, it's the "particle in a 1-d box problem.)
> 
> If I just do: DSolve[{y''[x] + k y[x]  ==  0}, y[x], x]
> it works fine, giving:
> {{y[x] -> C[2] Cos[Sqrt[k] x] + C[1] Sin[Sqrt[k] x]}},
> which is perfectly ok.
> 
> But if I include the boundary conditions y[0] == y[a] == 0,
> it doesn't work.
> 
>     Any ideas?
> --
> -----------------------------------------------------------------
> Gustavo Seabra - Graduate Student
> Chemistry Department
> Kansas State University
> -----------------------------------------------------------------
> 
> 
> 



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