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