> Q: why is ug not computed automatically, since lg is?
To be honest, I don't remember, but let me take an educated guess: depending
on the algebraic complexity of lg, the automatic calculation of ug may be
prohibitively costly, and in many cases, ug is not needed when a frame base
is used. Given this and the fact that if needed, ug can be computed
trivially may be the reason. (May have been _my_ reason. It was too long
ago, I just don't remember how much of this is code I wrote vs. code I
"rescued" from earlier, incomplete implementations.)
> would it be appropriate/correct to add a reference to see `petrov'?
You mean as a usage example? Yes, I think it would be appropriate.
Viktor
-----Original Message-----
From: maxima-bounces at math.utexas.edu [mailto:maxima-bounces at math.utexas.edu]
On Behalf Of Leo Butler
Sent: Monday, September 30, 2013 8:47 AM
To: Viktor T. Toth
Cc: maxima at math.utexas.edu
Subject: Re: [Maxima] Ctensor.texi parenthesis adjust
> From: "Viktor T. Toth" <vttoth at vttoth.com>
> Date: Sun, 29 Sep 2013 18:44:15 -0400
>
> Actually, the closing parenthesis should be after the word 'cmetric'.
The
> parenthetical remark explains that lg is computed automatically (from
the
> frame base) when the cmetric() function is called. This step may then
> followed by computing ug, which is not computed automatically by
cmetric()
> when cframe_flag is true.
Thank you for the correction, Viktor, and apologies for the noise.
Q: why is ug not computed automatically, since lg is?
In any event, would it be appropriate/correct to add a reference to
see `petrov'? It seems that the example there illustrates the intended
meaning of this paragraph, yes?
>
> Years ago, when I spent a lot of time working on the tensor packages, I
> updated much (but not all) of the Ctensor/Itensor documentation. At the
> time, my goal was simply to make sure that there are no obvious gross
> mistakes in the documentation and that all features are described,
however
> briefly. I also created several tensor examples. I've been meaning to
> incorporate these examples into the documentation in some tutorial form.
The
> difficulty is the usual one: only 24 hours in a day, only 7 days in a
> week... Still, I swear I'll do it one of these days :-)
:-)
Leo
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