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MathGroup Archive 2006

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Re: Symbolic Derivatives of Unspecified Functions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg70732] Re: Symbolic Derivatives of Unspecified Functions
  • From: David Bailey <dave at Remove_Thisdbailey.co.uk>
  • Date: Wed, 25 Oct 2006 01:39:58 -0400 (EDT)
  • References: <ehf1mp$5e9$1@smc.vnet.net> <ehhqlj$7cm$1@smc.vnet.net> <ehkc7f$hjf$1@smc.vnet.net>

Hello,

A definition such as r[qi_,qj_]:=r[qi,qj] (or the equivalent using =) is 
meaningless - it simply defines r in terms of itself - this sends 
Mathematica into a spin, which produces your iteration limit error. I am 
sorry if you thought I was suggesting this - I was merely quoting a bit 
of your original message!

The crucial thing to understand is that you can differentiate a function 
(or use it in other ways) without providing any definition at all - this 
is the appropriate thing to do.

David Bailey
http://www.dbaileyconsultancy.co.uk


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