Re: Re: Replacement question

*To*: mathgroup at smc.vnet.net*Subject*: [mg35186] Re: [mg35184] Re: [mg35114] Replacement question*From*: Omega Consulting <omega_consulting at yahoo.com>*Date*: Sat, 29 Jun 2002 01:37:42 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

At 01:32 AM 6/28/2002, Andrzej Kozlowski wrote: >I am not sure it is right to say the Omega Consulting method is superior >for all such situations, because the two methods are not equivalent and >in certain instances will give different answers. Holding everything >unevaluated till the end is not always the best choice. I also would not claim it is superior in all situations. But I would claim that it is a nice way to replace part of an unevaluated input, which is what was originally asked for. >Here is a very >quickly produced and rather artificial example but I am sure one can >find more natural ones: > >(example omitted) Such is life in the world of unevaluated expressions. When the evaluation takes place is critical to the result you get. There are hundreds of different variations and tricks to controlling when evaluation takes place. You have to be very careful that what you do is what you want. For those who haven't taken a look at it before, I would highly recommend http://library.wolfram.com/conferences/devconf99/villegas/UnevaluatedExpressions.nb It does a good job of laying out what unevaluated expressions are about and what you can do with them. -------------------------------------------------------------- Omega Consulting "The final answer to your Mathematica needs" Spend less time searching and more time finding. http://www.wz.com/internet/Mathematica.html