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Manipulating differential equations

• To: mathgroup at smc.vnet.net
• Subject: [mg18552] Manipulating differential equations
• From: Martin Heimann <martin.heimann at bgc-jena.mpg.de>
• Date: Sat, 10 Jul 1999 02:18:47 -0400
• Organization: mpi
• Sender: owner-wri-mathgroup at wolfram.com

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
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Email: martin.heimann at bgc-jena.mpg.de

• Follow-Ups:
  • Re: Manipulating differential equations
    • From: "Wolf, Hartmut" <hwolf@debis.com>
  • Re: Manipulating differential equations
    • From: "Carl K.Woll" <carlw@fermi.phys.washington.edu>