Re: Types in Mathematica, a practical example

*To*: mathgroup at smc.vnet.net*Subject*: [mg62855] Re: Types in Mathematica, a practical example*From*: "Steven T. Hatton" <hattons at globalsymmetry.com>*Date*: Tue, 6 Dec 2005 23:10:31 -0500 (EST)*References*: <dn22cf$ku4$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Ingolf Dahl wrote: > I am not allowed to Unset or Clear any part of a list either. Why not? I should probably look into this more carefully before commenting, but, at the risk of making an incorrect statement, I will say this. Lists and other entities in Mathematica are rewritten upon each evaluation. You never really modify an existing expression. Instead, you modify a copy, and assign the result to the original symbol. My explanation is almost certainly an oversimplification in need of refinement, but I believe it addresses the essence of your question. -- The Mathematica Wiki: http://www.mathematica-users.org/ Math for Comp Sci http://www.ifi.unizh.ch/math/bmwcs/master.html Math for the WWW: http://www.w3.org/Math/