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 | |