On Tue, 7 Dec 1999, Seak, Teng-Fong wrote:
> Jules Bean wrote:
>
> > On Tue, 30 Nov 1999, Seak, Teng-Fong wrote:
> >
> > > I don't understand quite your question. Maybe we've got some
> > > misunderstanding :-) Actually, I knew how to enter {}. When I ask Lyx
> > > to support R_{i}{}^{j}{}_{kl}, I wanted in fact LyX not to display the red
> > {}
> > > to make the tensor look a bit better.
> >
> > There are two quite orthogonal issues here:
> >
> > [snipped]
> > 1) Availability of font characters: LyX uses a set of X-windows fonts.
> > These have in them some approximation to many of the commonly wanted
> > characters in mathematical notation, but by no means all of them. LyX will
> > not be able to support the others without new fonts - and possibly a more
> > extendable font system.
>
> No, no, there's nothing to do with font. Have you tried that expression
> that I'd written, by the way? Well, except if you're talking about invisible
> font for displaying {} in the mathbox :-)
That was with reference to your other message, about blackboard bold :-)
>
> > 2) Previewing complex things may not be worth it. TeX is an extremely
> > complex system, dealing well with a variety of very complex on-page
> > display issues. It may not be appropriate for LyX to attempt to solve
> > some of these complex problems independently -- it's only intended to be a
> > WYSIWYG previewer.
>
> The expression R_{i}{}^{j}{}_{kl} is nothing fancy. It's at the base of
> LaTeX. No auxiliary macro is needed, neither is it an extension to the
> standard. It's just because this is seldom used so people might have
> forgotten it.
It's not even that seldom used. There's plenty of common TeX idioms that
LyX can't preview. My point is that LyX isn't a complete TeX renderer, so
the dev-team have made decisions about which TeX constructs it can
understand. In fact, I think LyX *should* preview the tensor construct,
but no one has written the code yet.
My point, I think, is that not supporting the tensor is not an oversight.
It simply hasn't been done, because there are so many things to do :-)
LyX's job is hard, because TeX is a bad document description language,
although it's a good page layout language.
Jules
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