Re: [O] [bug][ox-latex] Captions in equations

From:	Vladimir Lomov
Subject:	Re: [O] [bug][ox-latex] Captions in equations
Date:	Mon, 20 Jan 2014 09:51:47 +0900
User-agent:	Mutt/1.5.22 (2013-10-16)

Hello,
** Rasmus [2014-01-19 15:19:40 +0100]:

> Vladimir Lomov <address@hidden> writes:

>> Hello,
>> ** Rasmus [2014-01-18 20:36:35 +0100]:

>>> Hi,

>>> This example produces invalid LaTeX code:

>>> #+CAPTION: test
>>> #+ATTR_LATEX: :mode math :environment pmatrix
>>> | \alpha | \beta | \gamma |

>>> Namely,

>>> \begin{equation}
>>> \caption{test text}
>>> \mathbf{H}=\begin{pmatrix}
>>>  \vdots & 0 & \vdots \\
>>>  \vdots & H & \vdots \\
>>>  \vdots & 0 & \vdots \\
>>> \end{pmatrix}.
>>> \end{equation}

[...]

>> IMHO, this is wrong approach. 

> I don't understand.

As I said, this is IMHO.

>> I would consider this example as a special way to generate a matrix
>> when exporting to LaTeX, then CAPTION is useless here. Also, HTML
>> export will give differently looking result.

> But it shouldn't.  It should produce a matrix as well, e.g. via
> MathJax.

At first, I wanted to write the following:

  And would will be if one doesn't use MathJax? For example, I prefer to
  use dvipng to generate PNG images (there are several reasons for
  this).  So, basically, this is a special case, and an user evidently
  knows about this.

But then I tried to export this example document to HTML with MathJax
and it fails. Consider these two examples: 'ex-tbl.org' and
'ex-tbl2.org' (attached to the message). After exporting first to html I
get 'ex-tbl.html' without MathJax, the second has MathJax but only for
formula. As I expected, problem occurs only for LaTeX export, due to a
bit weird combination.

I'm not a mathematician but I read many books on mathematics and
theoretical physics (I'm a physicist) and don't remember examples of use
an equation with a caption. Equation enclosed into a frame, yes, I see
and use that, numbered or tagged equations, even placed into a float
(though didn't try yet).

Again, this was my IMHO. And I can't imagine situation when I would need
a caption for equation, because there are other ways to emphasize an
equation. What I see from this special example is how it is convenient
to create a matrix for "math mode" in Org document.

> –Rasmus

---
WBR, Vladimir Lomov

-- 
  Monotheism is a gift from the gods.