Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
1998
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 1998

[Date Index] [Thread Index] [Author Index]

Search the Archive

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