real valued solutions?
- To: mathgroup at smc.vnet.net
- Subject: [mg23449] real valued solutions?
- From: Robert <robert.schuerhuber at gmx.at>
- Date: Wed, 10 May 2000 02:32:28 -0400 (EDT)
- Organization: Vienna University of Technology, Austria
- Sender: owner-wri-mathgroup at wolfram.com
i guess my problem is rather simple to solve, but i counld't figure it
out :-(
i'd like to solve ordinary differential equations with constant
coefficients with mathematica, where everything is real-valued. so the
solution is real-valued, too. how can i avoid the complex exponentials
in the solution?
e.g.
DSolve[{y''[x]-y'[x]+y[x]==0,y[0]==1,y'[0]==0},y[x],x]
gives
{{y[x]->Exp[-(-1)^2/3 x ( ... }}
as the result instead of the real-valued solution y[x]=Exp[x/2]
(Cos[Sqrt[3]/2 x]-1/Sqrt[3] Sin[Sqrt[3]/2 x).
robert