Re: Manipulating differential equations
- To: mathgroup at smc.vnet.net
- Subject: [mg18576] Re: Manipulating differential equations
- From: "Kevin J. McCann" <kevinmccann at Home.com>
- Date: Tue, 13 Jul 1999 01:01:19 -0400
- Organization: @Home Network
- References: <7m6jti$2mc@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Try this: f[x_]=Exp[a x]; dg2=dg1/.c->f Kevin Martin Heimann <martin.heimann at bgc-jena.mpg.de> wrote in message news:7m6jti$2mc at smc.vnet.net... > Dear colleagues, > > I would like to insert test functions into an expression that contains > differentials: > > dg1 = c''[x] + g c'[x] > > I would like e.g. to replace c[x] by Exp[-a x]: > > dg1/.c[x]->Exp[-a x] > > but this doesn't work; one has to put substitution rules for each of the > derivatives explicitly. Is there a more elegant way to achieve this? > > Cheers, > Martin Heimann > ------------------------------------------------------------------ > Max-Planck-Institut fuer Biogeochemie > Postfach 100164, D-07701 Jena, Germany > (Street Address: Tatzendpromenade 1a) > > Tel.: +49-3641-64-3773/3701, Fax.: +49-3641-64-3710 > Email: martin.heimann at bgc-jena.mpg.de >