Re: simple question on DSolve

*To*: mathgroup at smc.vnet.net*Subject*: [mg124978] Re: simple question on DSolve*From*: Bob Hanlon <hanlonr357 at gmail.com>*Date*: Wed, 15 Feb 2012 04:44:12 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201202141137.GAA17715@smc.vnet.net>

eqns = {y''[x] + k*y[x] == 0, y'[0] == yp0, y'[1] == yp1}; sol = DSolve[eqns, y, x][[1]] // Simplify {y -> Function[{x}, (1/Sqrt[ k])(yp0 Cos[Sqrt[k] x] Cot[Sqrt[k]] - yp1 Cos[Sqrt[k] x] Csc[Sqrt[k]] + yp0 Sin[Sqrt[k] x])]} eqns /. sol // Simplify {True, True, True} y[x] /. sol /. {yp0 -> 0, yp1 -> 0} 0 Appears to be forced by boundary conditions. Bob Hanlon On Tue, Feb 14, 2012 at 6:37 AM, Gualtiero Badin <gualtiero.badin at gmail.com> wrote: > Hello, > if I try to solve the simple boundary value problem > > y''+ky=0 > y'(0)=0 > y'(1)=0 > > mathematica returns me y=0, that is correct but that is not the > complete answer... Does anyone know how to get the complete answer? > (of course i know the complete answer, but I would like to solve some > uglier versions of the same problem...) > Thanks

**Follow-Ups**:**Re: simple question on DSolve***From:*Christoph Lhotka <christoph.lhotka@fundp.ac.be>

**References**:**simple question on DSolve***From:*Gualtiero Badin <gualtiero.badin@gmail.com>