Re: math symbol: blacktriangle

[Andreas Mang <mang@imt.uni-luebeck.de>]

Hi Hans,


> On 17-7-2012 20:41, Andreas Mang wrote:
>> mathname="blacktriangle",
>> 
>> to
>> 
>> [0x25B4]={
>>   adobename="blackuppointingsmalltriangle",
>>   category="so",
>>   description="BLACK UP-POINTING SMALL TRIANGLE",
>>   direction="on",
>>   linebreak="al",
>>   unicodeslot=0x25B4,
>>  },
> 
> why not 25B2 (the bigger one)
>> 
>>  [0x25BE]={
>>   category="so",
>>   description="BLACK DOWN-POINTING SMALL TRIANGLE",
>>   direction="on",
>>   linebreak="al",
>>   unicodeslot=0x25BE,
>>  },
>> 
>> with mathname="blacktriangledown" under the assumption you'd like to be consistent with the naming convention of latex.
> 
> or 25BC (the bigger one)

To make it short: I think Hans is correct. From my perspective there is an error in char-def.lua for "blacktriangleleft" and secondly the internet page I have looked this up is not consistent with what is implemented in ConTeXt, both facts of which lead me into the wrong direction (see below (P.S.), if you are interested).

Both,

http://www.unicodemap.org/details/0x25B2/index.html

and

http://www.unicodemap.org/details/0x25BC/index.html

look consistent to "\blacktriangleright" (which I am already using in my document):

http://www.unicodemap.org/details/0x25B6/index.html

Cheers,
Andreas


P.S.: When I started to look into this I thought it might be possilble to define some command in the preamble of my document that uses unicode. From searching the internet I found 

http://www-sop.inria.fr/marelle/tralics/doc-b.html

which says "The \blacktriangle command is valid only in math mode. Its translation is <mo>&blacktriangle;</mo> (Unicode U+25B4, ▴)".

However, there indeed is a problem (which I have not spotted in the first place). I had a look at char-def.lua which at first confirmed my impression on using small triangels: 

 [0x25B8]={
  category="so",
  description="BLACK RIGHT-POINTING SMALL TRIANGLE",
  direction="on",
  linebreak="al",
  mathclass="bin",
  mathname="blacktriangleleft",
  unicodeslot=0x25B8,
 },

However, this is not consistent with what you can find on the internetpage from above, since it "0x25B8" should be "blacktriangleright" 

"The \blacktriangleright command is valid only in math mode. Its translation is <mo>&blacktriangleright;</mo> (Unicode U+25B8, ▸)." 

Secondly, the \triangleleft, which I have not used before, does not work (at least for me ConTeXt  ver: 2012.07.10 09:52 MKIV fmt: 2012.7.15 int: english/english):

simple example: 

%%%%%%%%%%%%
\starttext
$\blacktriangleleft$ % does not appear
$\blacktriangleright$ % works
\stoptext
%%%%%%%%%%%%

For the blacktriangleright we have:

 [0x25B6]={
  adobename="blackrightpointingtriangle",
  category="so",
  cjkwd="a",
  description="BLACK RIGHT-POINTING TRIANGLE",
  direction="on",
  linebreak="ai",
  mathclass="bin",
  mathname="blacktriangleright",
  unicodeslot=0x25B6,
 },

which is _not_ consistent with "The \blacktriangleright command is valid only in math mode. Its translation is <mo>&blacktriangleright;</mo> (Unicode U+25B8, ▸)."

However, looking at http://www.unicodemap.org/details/0x25B6/index.html and given the fact that "blacktriangleright" works nicely, I'd assume that Hans is correct and it indeed is not the small ones but the big tirangles.
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