[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Math Arrows and Harpoons

i have examined most of taco's arrows and harpoons, and have found
some problems.

do i understand correctly that 221 is the maximum size of a type 1
font that's to be used in applications other than tex?  there are a
few additional items that might be considered here, but if this is
already at maximum, some negotiation might be necessary.

i didn't find any problems with the shapes up through 119 (although
i thought that the fishtail in 106 would better have been switched
with the one in 143; more on that later).  i do see a problem with
the shapes in 120, 121 and 123, and perhaps 122; i'm still checking
the ones after that.

the arrows in 120, 121 and 123 should definitely have the arrowheads
pointing up at an angle, rather than horizontal.  the shape of the
wavy stem is more-or-less that of a similar sign (or its mirror
image).  this is how they appear in both the unicode manual and the
afii glyph register; in the latter, the rightwards version has a
subsidiary meaning/description "functional relationship", which i
think may have come from the iso tech report 9573-13, which has a bit
of a physics orientation.

the arrow in 122, in both the unicode manual and afii glyph register,
has an "up" wave in the middle; taco's has a "down" wave.  again, i
think this may have come from iso tr 9573-13.

i couldn't find a negated version of the leftwards wavy arrow -- have
i missed something?

the names already used for these arrows (in lasy and the amsfonts)
are different from what taco has, but in all, i think i like taco's
names better:

    120 rightwavyarrow       rightsquigarrow (ams), leadsto (lasy)
    121 leftwavyarrow        leftsquigarrow (ams)
    122 leftrightwavyarrow   leftrightsquigarrow (ams)
    123 nrightwavyarrow

(the unidirectional arrows in the ams fonts are also a somewhat
different shape, but in the absence of actual published examples,
i'm unable to make any useful distinction.)

hans aberg commented on the fishtails in an earlier message, saying
that he doubted that these are used by themselves, as opposed to being
part of some composite.  i've never seen (and am desparately looking
for) published examples, but from the unicode, afii, and iso tr 9573-13
evidence, believe that they are indeed individual symbols.  i don't
know the difference between 089 and 106; however, 089 has a meaning in
the afii register "element precedes under relation", a meaning that in
the unicode manual is assigned to something that looks like a less-than
sign with the arms heavily curved out and back on themselves.  (in the
stix collection, i positioned these after arrows because they are
directional; i don't believe that they really do have anything to do
with arrows.)  there is a naming problem here too -- both 089 and 106
are named "rightfishtail"; 106 is the one that should change -- i
suggest varrightfishtail since it is the odd one out.

another naming overlap: 087 and 111 are both named Mapsto.  since
the initial cap on most other arrows denotes a doubling of the stem,
i think that 111 should keep this name, and 087 should be renamed to
twoheadmapsto following the model of 015, twoheadrightarrow.

i'm having a problem with the naming of the vertical harpoons.  the
horizontal harpoons are consistently named (following the plain tex
names) shaft direction-harpoon-barb direction, e.g. leftharpoonup.
this pattern was followed in the amsfonts for the vertical harpoons,
e.g. upharpoonleft; however, taco has used the pattern (vertical
only) shaft direction-barb direction-harpoon, e.g. upleftharpoon.
i would prefer that the plain tex pattern be maintained throughout
for single-barbed harpoons (both because it seems to make sense and
quite a few names have already been assigned in the amsfonts).
this affects the following (order of names is current / proposed):

    036 uprightharpoon         upharpoonright
    037 upleftharpoon          upharpoonleft
    040 downrightharpoon       downharpoonright
    041 downleftharpoon        downharpoonleft

    150 baruprightharpoon      barupharpoonright
    151 downrightharpoonbar    downharpoonrightbar
    152 uprightharpoonbar      upharpoonrightbar
    153 bardownrightharpoon    bardownharpoonright
    154 barupleftharpoon       barupharpoonleft
    155 downleftharpoonbar     downharpoonleftbar
    156 upleftharpoonbar       upharpoonleftbar
    157 bardownleftharpoon     bardownharpoonleft

there's a problem with the ordering of the names vs. the shapes here:
what i have listed as 150-153 is 149-152 in taco's list, with the
name at 153 belonging to the shape at 149.  (it would be a whole lot
easier to check these names if the shapes were next to them.  i know
this is asking a lot ...)

there are two harpoon pairs that already had names, one from plain
and the other from amsfonts, simpler than the ones taco lists; taco's
are more "exhaustive" in their descriptive content, but i think the
simpler forms are reasonable to keep as equivalents:

    049 leftharpoonuprightharpoondown  leftrightharpoons (amsfonts)
    050 rightharpoonupleftharpoondown  rightleftharpoons (plain)

i'm still contemplating the names for the double and two-barbed
harpoons.  i think i like the following better than what taco has
proposed, but am willing to be persuaded otherwise.  (the horizontal
double and two-barbed harpoons are well named as is.)

    091 downleftharpoonuprightharpoon    downharpoonleftupharpoonright
    092 upleftharpoondownrightharpoon    upharpoonleftdownharpoonright
    093 upleftharpoonuprightharpoon      upharpoonleftupharpoonright
    094 downleftharpoondownrightharpoon  downharpoonleftdownharpoonright

    146 leftdownrightupharpoon           updownharpoonrightleft
    147 leftuprightdownharpoon           updownharpoonleftright
    148 rightuprightdownharpoon          updownharpoonrightright
    149 leftupleftdownharpoon            updownharpoonleftleft

the last group i'll address now is the accents.  some of these have
names already from plain tex different from what taco has listed.

    207 leftarrowaccent        overleftarrow
    208 rightarrowaccent       overrightarrow  or  vec
    209 leftrightarrowaccent   overleftrightarrow

i noticed the absence of vertical arrow fillers; these are just as
likely to be needed, i think, as horizontal ones.  and i've also seen
a request for long triple-stem horizontal arrows, so Lleftarrowfiller
and Rrightarrowfiller might be considered.  (but none of these fillers
are candidates for addition to unicode.)

i still haven't checked every single name or association, so there
will probably be a (very) brief addendum to this in a few days.

i will be adding all the names i have checked already, which don't
yet appear in my stix project list; i will use the names in the
right-hand column in the lists of questions above, except for the
wavy arrows as already mentioned.

i am still really looking for help in finding documentation for these;
please take a look at the ams symbols challenge -- there's a pointer
on the main ams web page (http://www.ams.org); please look at the
archive as well as this week's selection, and at the "complete symbols
collection" that identifies what will be submitted to the unicode
technical committee at their meeting the first week of december.
							-- bb