Re: differential equation with buondary conditions

*To*: mathgroup at smc.vnet.net*Subject*: [mg30319] Re: [mg30313] differential equation with buondary conditions*From*: "peter lindsay" <plindsay at dcs.st-and.ac.uk>*Date*: Sat, 11 Aug 2001 03:39:42 -0400 (EDT)*References*: <200108080534.BAA04457@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

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 > ----------------------------------------------------------------- > > >

**References**:**differential equation with buondary conditions***From:*Gustavo Seabra <gseabra@swbell.net>