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Re: Displaystyle and mtable

From: Peter Krautzberger <peter.krautzberger@mathjax.org>
Date: Thu, 18 Sep 2014 23:09:45 +0200
Message-ID: <CABqxo80t5DLWyz3BQLvR1XOzcqCda1qSDavGWiUj0CCb8xof0w@mail.gmail.com>
To: David Carlisle <davidc@nag.co.uk>
Cc: "www-math@w3.org" <www-math@w3.org>
Thanks, David, for confirming the reading of the spec.

So to guarantee \displaystyle we're supposed to do something like

<mstyle scriptlevel="0">
<mtable displaystyle="true">
...
</mtable>
</mstyle>

To guarantee \textstyle something like

<mstyle displaystyle="true" scriptlevel="0">
<mtable>
...
</mtable>
</mstyle>

And

<mfrac>
<mtable displaystyle="true">
...
</mtable>
<mrow>
...
</mrow>
</mfrac>

would get us a table with displaystyle formatting, but in scriptstyle size
(when used in an inline formula). (I admit I find that somewhat strange; oh
well.)

Thanks again for your quick response!
Peter.

On Thu, Sep 18, 2014 at 5:07 PM, David Carlisle <davidc@nag.co.uk> wrote:

> On 17/09/2014 20:37, Peter Krautzberger wrote:
>
>> Hi everyone,
>>
>> A follow-up question after Fred commented
>> <https://github.com/dpvc/MathJax/commit/98e3f098bd519dabe9bf558736c5bf
>> 6438fbc217>
>> on our changes to MathJax (following the results of this discussion);
>> these changes include resetting the scriptlevel to 0. To us, this
>> seemed to make the most sense after the discussion: if display style
>> wasn't supposed to be inherited, then scriptlevel seemed strange to
>> inherit (also, there were some "matching TeX behavior" comments on
>> this thread).
>>
>> To put it differently, we couldn't imagine how an author setting
>> displaystyle to "true" would expect to stay at scriptlevel=1 (for
>> example). The only use-case we could think of would be an array in a
>>  superscript or fraction, but this doesn't seem very likely.
>>
>> However, as Fred pointed out, the spec seems to read differently.
>> Since displaystyle needed to be clarified, we thought it's best to
>> ask for clarification on this as well.
>>
>> Thanks in advance, Peter.
>>
>>
> I think the spec is clear, and the splitting of tex's \xxxstyle concept
> into two separately settable parameters was certainly intentional:
>
> 3.1.6 says
>
>  TEX's \displaystyle, \textstyle, \scriptstyle, and \scriptscriptstyle
>> correspond to displaystyle and scriptlevel as "true" and "0", "false"
>> and "0", "false" and "1", and "false" and "2", respectively.
>>
>
>
>
> That choice inevitably means that there are combinations not reachable
> in TeX (and thus uncommon to most authors and probably unlikely
> to be used except in exceptional circumstances) but I think it's clear
> that the spec intends that they are reachable.
>
>
>
> David
>
>
>
>
>
>
Received on Thursday, 18 September 2014 21:10:12 UTC

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