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Message-ID:  <9704101205.AA08054@sgibulirsch6.mathematik.tu-muenchen.de>
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In-Reply-To:  <Pine.SOL.3.93.970410115619.27446C-100000@sun2> from "Matthias
              Clasen" at Apr 10, 97 12:07:02 pm
Date:         Thu, 10 Apr 1997 14:05:44 +0200
From: Johannes Kuester <kuester@MATHEMATIK.TU-MUENCHEN.DE>
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To: Multiple recipients of list LATEX-L
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Subject:      Re: math fonts
Status: R

Matthias Clasen wrote:

>                             Splitting MX ?

Yes, definitely. This always seemed to me to be the major weak point of
Justin's proposal, as this is too rigid, too restrictive. I think
there are enough glyphs to make up a second extension font, at least.

Of course, the first one should contain the usual TeX glyphs, as proposed,
and the second (and may be third,..) one then should contain the others.

> If the new big delimiters are no longer in the first 6 families, there is
> not much point in keeping their basic size counterparts in MC. These
> should also go to MX2, freeing some valuable slots in that encoding.

Some comments on MC: the ordering of the Greek glyphs seems to be somewhat
arbitrary, they should either be ordered in the order of the Greek
alphabet or according to the input conventions of e.g. Haralambous's
Greek fonts (I think the first is preferable, but the current alpha,beta,
delta,... gives a new ordering never to be seen so far). I also think that
upright and slanted/italic glyphs should reside at a multiple-of-8 distance
in the font; e.g. upright Alpha at "81, slanted Alpha at "B9, to make
then more easily findable and comparable. There are some glyphs for
which I don't see any reason for being in the core, namely "5F, "61,
"F8 and "F9 (barred V, upright and slanted, thorn (variant) and Thorn),
as they are very rarely used in mathematics (if at all?). Justin didn't
give any example of their usage. Also, to include the upright "d" seems
arbitrary, as other upright glyphs aren't taken into account.
  Freeing some slots could be advantageous, but for some delimiters the
reason to reside here is kerning, so this should be considered before
taking them elsewhere.

  Oh, and the digits should be upright, I think, as slanted/italic digits
should not appear in mathematics.

>  - moving *all* charlist-accessed glyphs (even the wide accents) out of
>    MC, MSP, MS1 and MS2 .

Consider kerning, taken them out of the fonts could well be quite
disadvantageous.
  I didn't like Justin's proposal at first, because doesn't seem to me
that it cleanses up the current mess of math fonts, but puts together
some new fonts which show the same mess only on a larger scale, but
I didn't think of kerning then: this is still the major restriction
here to make deliberate decision and putting different groups in different
fonts (this restriction won't be overcome in TeX, though). So here
Justin made some very valuable points: to get proper kerning at least
with the most important symbols, one has to keep things in the same font
here. And the basic sizes of the delimiters occur more often than their
extended counterparts, so I think they should kern properly e.g. with
italic letters.

>  - there is now enough room in MX2 to add some more wide accents, like
>    wide triangles or parens (found in yhmath).

And there should be upright versions of all the integral sings (as the
integral falls under the "upright type rule" discussed here before; to
be consistent in using this rule, these glyphs are needed.

I have metafonted a few glyphs which I could contribute
(in rather poor METAFONT, as these were among my first glyphs,
but I think they look the right way, even when their programs need
to be polished). Namely:

interval delimiters (with extensibles)
   (to be found in Duden, used e.g. in "dtv-Atlas zur Mathematik";
    quite useful to denote intervals unambiguous, as the usual "(a,b)"
    is one of the most overloaded notation in mathematics)

"medium" and "sharp" angle brackets (with extensibles)
   (useful to make at least a slight distinction for the reader,
    when notating different concepts with angle brackets)

the Vinogradoff symbols for the order of a function
   (looking like < and > with another angle inside, I think these
    should have their own glyphs, as their meaning is quite different
    from "much less than" and "much greater than")

arrows for surjection (double arrowhead), injection (arrowhead and -tail)
    and bijection (arrowtail and double arrowhead)
    (found in Duden, could be covered by the arrowkit package, I suppose
     (how about the double arrowhead?), quite useful sometimes)

a special symbol for the Laplace operator and a matching Nabla
    (looking like a \bigtriangle, a bit larger and bolder though;
     may be useful as I think \Delta (the upright one for Laplace) is
     overused and ambiguous)

a "does not divide" symbol
    (TeX's slash for negation doesn't work here properly, and the AMS
     symbol for this seems to have a negation slash which is too short)

upright lowercase Greek glyphs
    (these are merely a matter of taste, I made them by "unslanting"
     the usual ones and changing the code when it seemed appropriate
     to get a goodlooking glyph. May be Greek has to be redesigned
     completely anyway, as I don't see a reason for having uppercase
     Greek letters which are undistinguishable for their Latin counterparts)

    Here again, Justin's proposal seems to be too restricted: There
    are at least two variant glyhs for each of Qoppa, qoppa, Sanpi and sanpi,
    and there is "stigma" (merely a sigma-tau ligature, to be found in
    Unicode), which hasn't been considered yet.

a big times-like symbol
a big bottom symbol
a big top symbol
(all of them in the two sizes of the extension font)


I agree that the "group" delimiters of TeX should be made available at
all sizes (they could be useful to distinguish different kinds of arguments,
e.g. in the theory of representations, or to give the Legendre symbol
a more distinct appearance from a fraction in parentheses etc.)

And as for font naming conventions: please do use preliminary names
for the fonts (how about "d" instead of "e" as a starting letter?).
I don't see a good reason for the naming "emsp", I think this should
just be the first math symbol font, named "emsa" ("dmsa" for now?),
the other names shifted accordingly, thus it will be privileged enough.

Johannes Kuester

--
Johannes Kuester                    kuester@mathematik.tu-muenchen.de
Mathematisches Institut der
Technischen Universitaet Muenchen