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Re: Re: Recalculating values in tables?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg63929] Re: [mg63922] Re: Recalculating values in tables?
  • From: ggroup at sarj.ca
  • Date: Mon, 23 Jan 2006 04:11:45 -0500 (EST)
  • References: <200601200932.EAA22054@smc.vnet.net> <dqspfk$cgk$1@smc.vnet.net> <200601220552.AAA09577@smc.vnet.net>
  • Reply-to: ggroup at sarj.ca
  • Sender: owner-wri-mathgroup at wolfram.com

On Sunday, January 22, 2006 at 12:52 AM, Aes wrote:

<snip>
>> > Or should I always take the messier of route of coding these functions
>> > explicitly in my initialExpressions using something like
>> 
>> Sure looks like it.

> For sure, in this case.  Good point.

> But this is not the kind of case I was considering; and I think I'd know 
> enough not to do something like this (even setting aside the fact that 
> n++ is not a structure I personally ever happen to use in writing 
> programs)

I wasn't trying to insult your skills. But as your question was very
general, n++ is a perfectly valid Mathematica construction.

Is there no way you could come up with a reasonable example that would
demonstrate what Mathematica actually does in your specific case? What
about changing the iterator so you only step through one line of each
table command? This way you might compare the evaluation times (see
Timing[]) directly of your specific code in a reasonable amount of
time.  You need to invest some time in testing your code while trying
to optimize evaluation.

There might be some caching that helps somewhat, but in general, how
could Mathematica be expected to know that something hasn't changed
between evaluations?  In my example the change is very obvious, but as
others have said, I think the assumption has to be that Mathematica
will reevaluate each time.



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