Re: System of differential equations

• To: mathgroup at smc.vnet.net
• Subject: [mg13596] Re: System of differential equations
• From: Paul Abbott <paul at physics.uwa.edu.au>
• Date: Mon, 3 Aug 1998 03:53:55 -0400
• Organization: University of Western Australia
• References: <6puhnm\$6r2@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Jens-Peer Kuska wrote:

> Your problem is solved with
>
> eqn={a y[z]-b s'[z]==0,d s[z]+f y'[z]+g s'[z]+h s''[z]==0}
>
> deqn=Append[eqn,D[#,z] & /@ eqn[[1]]]
>
> Eliminate[deqn,{y[z],y'[z]}]

An alternative, which avoids having to work out which equation to
differentiate, is

eqn={a y[z]-b s'[z]==0,d s[z]+f y'[z]+g s'[z]+h s''[z]==0}

deqn = Flatten[{eqn, D[eqn, z]}];

Eliminate[deqn, {y[z], y'[z], y''[z]}]

Cheers,
Paul

____________________________________________________________________
Paul Abbott                                   Phone: +61-8-9380-2734
Department of Physics                           Fax: +61-8-9380-1014
The University of Western Australia            Nedlands WA  6907
mailto:paul at physics.uwa.edu.au  AUSTRALIA
http://www.physics.uwa.edu.au/~paul

God IS a weakly left-handed dice player
____________________________________________________________________

• Prev by Date: Re: Block diagonal systems
• Next by Date: Publicon Problems
• Previous by thread: Re: What is the fastest machine for Mathematica?
• Next by thread: Publicon Problems