Re: symbolic solution of ODE

*To*: mathgroup at smc.vnet.net*Subject*: [mg71514] Re: symbolic solution of ODE*From*: "dimitris" <dimmechan at yahoo.com>*Date*: Tue, 21 Nov 2006 07:05:11 -0500 (EST)*References*: <ejtdfo$iva$1@smc.vnet.net>

Hello. First the solution of your ODE. sol = DSolve[Derivative[4][w][z] - 2*t*Derivative[2][w][z] + k*w[z] == 0, w[z], z, GeneratedParameters -> (Subscript[c, #1] & )] Let's check it. derfun = Flatten[(D[sol, {z, #1}] & ) /@ Range[0, 4]]; FullSimplify[Derivative[4][w][z] - 2*t*Derivative[2][w][z] + k*w[z] == 0 //. %] True >...imposing the condition "t^2 < k"... Did you mean something like the following? w[z] /. FullSimplify[sol /. -k + t^2 -> -m^2, m > 0][[1]] Dimitris visbuga at purdue.edu wrote: > Hello, > > I like to solve the ODE > DSolve[w''''[z] - 2*t*w''[z] + k*w[z] == 0, w[z], z] > by imposing the condition "t^2 < k" on constants in the eqn.In fact, solution > of this homogenous ODE is known, but I want to see the result of mathematica > to use in a complex eqn. Thank you. > > VV