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Re: Use of Mathematica with Rule-based Equation Derivations

• To: mathgroup at smc.vnet.net
• Subject: [mg61927] Re: Use of Mathematica with Rule-based Equation Derivations
• From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
• Date: Sat, 5 Nov 2005 01:52:09 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

set up a global list of your constants and check the symbol if it is a
member of that list.

Regards
  Jens

<mmorriss at gcn.ou.edu> schrieb im Newsbeitrag 
news:dkfd8o$etv$1 at smc.vnet.net...
| Hi All - I'm a many-year user of mathematica, 
but have always had one
| particular problem with it that I may have just 
simply missed reading
| about.
|
| Mathematica Version: 5.2
|
| Problem: I would like to develop a set of 
re-rewite rules to apply to the
| Expected Value operator.  For example:
|
| E[a x] = a E[x]  a -> constant, x -> variable
| E[b + f[x]] = b + E[f[x]] , etc.
|
| The issue is how does one using Mathematica 
distinguish a 'constant
| variable (i.e. a and b)' from a variable 
'variable' (i.e. 'x')? The head
| of a, b and x is 'Symbol' and neither a, b nor x 
contain a number so I
| can't use a_?NumberQ to identify it as a 
constant.
|
| This actually goes to the wider question of how 
does one use Mathematica
| for symbolic derviations where numbers are not 
actually substituted in the
| derviation?
|
| E.g. E[a + E[b x]] /. Rule2
|   out= a + b E[x] etc.
|
| Thanks all - Mark Morrissey
| University of Oklahoma
|
|