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 ____________________________________________________________________