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## RE: [Axiom-developer] [TeXmacs]

 From: michel . lavaud Subject: RE: [Axiom-developer] [TeXmacs] Date: Mon, 20 Dec 2004 12:12:43 +0100

Hello Bill,

On 19 Dec 2004 at 0:41, Bill Page wrote:

>   I1 := integrate (1/(x**3 * (a+b*x)**(-1/3)),x)
>
> > and the result appears to have big left and right parentheses,
> > but the first two lines are incorrect.
>
> Actually if you look closely, it is correct but just formatted
> in a rather unexpected style. To see this try
>
>   numer(I1)
>
> You will notice that in the full expression, the first term of
> the numerator has been folded locally at the \cdot into two lines with
> a leading minus sign vertically centered on the right like this
>
>    b^2x^2\sqrt{3} \cdot
> -                               + 2b^2x^2\sqrt{3}log(sqrt[3]{-a^2} ...
>    \log(sqrt[3]{-a^2}^2 ...
>
> This type of "nested folding" is actually built in to Robert
> Sutor's algorithm. There may be an option that I am not explicitly
> setting which controls this type of behaviour.

Ah OK ! you are right, everything is there, although the formula is nonsense
normally. So, on this example, it is Sutor's algorithm that is broken, and
TeXmacs
renders Sutor's output correctly, except that it imports incorrectly the "l"
parameter of
arrays into a "c" parameter.

In Sutor's output, the three lines you mention are constructed as an array
embedded in
the main array, and it seems there is an end of line \\ which is inserted
incorrectly
inside this embedded array, while it ought to be after the \end{array}.
Otherwise, there
ought to be a \left( just before the embedded array, and a \right) after its
end, for the
LaTeX output to be correct mathematically ; and this is apparently not what was
intended, as these are absent, and as the rest of formula is on the right
being below.

>
> http://page.axiom-developer.org/zope/mathaction/VeryLongLaTeX
>
> I am glad to see that all of these examples work on MathAction
> since MathAction is actually using LaTeX internally to do the
> formatting. So this represents a reasonable "benchmark" against
> which to compare the TeXmacs output.

Well, I don't really agree on this point ? For me, the last formula on the web
page does
not appear "a little odd at first sight", it appears incomprehensible...

> I think that the more we (Axiom developers) depend on TeXmacs,
> the more we must be prepared to try to help maintain TeXmacs -
> just as we already have a great (sometimes two-way) relationship
> with the GCL developers, on which the current version of Axiom
> strongly depends ... :)

While Axiom depends on gcl, it does not depend on TeXmacs. I think we ought to
privilege rigor, not ease of use. For education or training with Axiom, TeXmacs
is very
nice. But for research, in my opinion, the default editor for Axiom ought to be
Emacs,
not TeXmacs. Some adaptation to Axiom of imaxima.el, by Jesper Harder, would be
vey nice, as it relies on TeX itself, and the new version of Emacs allows to
include
images, on Linux and Windows. So, beautiful output and rigor can coexist.

Best wishes,

http://www.univ-orleans.fr/EXT/ASTEX
ftp://ftp.univ-orleans.fr/pub/tex/PC/AsTeX