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Delayed Derivative Operator

• To: mathgroup at smc.vnet.net
• Subject: [mg81762] Delayed Derivative Operator
• From: ToddSmith <elliptic1 at gmail.com>
• Date: Wed, 3 Oct 2007 02:26:48 -0400 (EDT)

Hi,
 I would like to be able to have an equation

eq := D[f[x],x]==5;

And a substitution rule

rule = f[x]->x^3;

And perform the substitution

eq/.rule

And get back the equation 3x^2==5. But Mathematica sees f'[x] and
doesn't do any substitutions. I tried a delayed assignment for eq but
it didn't work. What can I do?

-Thanks

• Follow-Ups:
  • Re: Delayed Derivative Operator
    • From: Curtis Osterhoudt <cfo@lanl.gov>
  • Re: Delayed Derivative Operator
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>