Re: unicode integral sign

[Taco Hoekwater <taco@elvenkind.com>]

Aditya Mahajan wrote:
> On Sat, 29 May 2010, Yury G. Kudryashov wrote:
> 
>> Taco Hoekwater wrote:
>>
>>> Yury G. Kudryashov wrote:
>>>> Hi!
>>>>
>>>> I try the following:
>>>>
>>>> \starttext
>>>> $∫_a^b \int_a^b$
>>>> \stoptext
>>>>
>>>> In the first case, the integral sign is below the text. Should I use
>>>> another font, or is it possible to fix with the default one?
>>>
>>> It is possible to fix this. The reason for the odd placement is that the
>>> 'math code' of ∫ is not set up properly (and it probably isn't either
>>> for some other bare Unicode characters). To fix the hard way, add this
>>> at the top of your input file:
>>>
>>> \Umathcode `∫ = 1 0 `∫ % 1 == \mathop, 0=fam0, ∫=glyph
>> Is there any documentation on char-def.lua file format? If I'll 
>> understand it, I'll send a patch for the symbols I use.
> 
> Not a complete documentation, but some explanation is here
> 
> https://www.tug.org/members/TUGboat/tb30-2/tb95mahajan-cmath.pdf
> 
>> Currently I have no idea why the following strings in char-def don't 
>> work.
>>
>> [0x222B]={
>>  adobename="integral",
>>  category="sm",
>>  cjkwd="a",
>>  description="INTEGRAL",
>>  direction="on",
>>  linebreak="ai",
>>  mathspec={
>>    { class="nothing", name="intop" },
>>    { class="limop"  , name="int"   },
>>  },
>>  unicodeslot=0x222B,
>> },
>>
>> Replacing mathspec=... with mathclass="limop", mathname="int" seems to 
>> work (copied from n-ary summation).
>>
>> BTW, in both solution ∫_a acts like \int\limits_a, not \int_a.
> 
> In plain TeX, this is taken care by
> 
> \mathchardef\intop="1352 \def\int{\intop\nolimits}
> 
> Can I do the same in luatex without active characters?

No, but it is a useful extension to consider. There are internally
three types of large operators, for 'limits', 'nolimits' and
'displaylimits' and this bothers me a bit. We can't reasonably
extend the old primitives, but \Umathcharcode c.s. could be made
to accept extra values '9' .. '11' for those three types without
any compatibility problems.  I'll add to the tracker.

Best wishes,
Taco


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