Re: [orca-list] Copying Math Expressions from Web pages

[Rastislav Kiss <rastislav kish gmail com>]

Hello,
it highly depends on concrete formula you're viewing.

The common html format for math expressions is called MathML. It allows
webpages to contain math formulas in a xml-like form, which is
supported by all major browsers and can be quite easily rendered.
There are two branches of MathML:
* Presentation markup
* Content markup

The firstone describes math expressions in a rather visual form. For
example, v^2 is represented as v with superscript 2 and its not
specified, whether the 2 is an index of a vector or a power.
The secondone focuses rather on meaning of expressions and their
individual parts, the previous example would be in this case either
specified explicitly as a power or index.

In practice, both branches are mixed together, so an author can make
use of both visual and semantic expressivity of MathML. The exact way
how this is done is... kind of more complicated, you can read more
about it if you want here:
https://www.w3.org/TR/MathML2/chapter5.html

Spoiler: after the first few sections, it gets superboring. :)

While presentation markup can be translated to correct math notation in
very simple equations, it gets significantly harder with more
complexones, that's the reason why there are not many MathML to LaTeX
convertors around. Such task needs heuristic, which may but also may
not work, depending on quality of algorithm and processed formula.
Content markup is ideal for back conversion, as it contains all
necessary informations without distracting elements.
Which markup is used in concrete formula highly depends on used
software, and the fact that they can be used both doesn't help it much.

Thus for copying these equations, I would most likely use a
mathematical software, which can deal with both markups to give you the
best possible results. I can't recommend you any specific as I didn't
need this myself, but there should be few of them around on the net.

And... if you're lucky, there is a third option. MathML contains a
semantic tag, which can be used to describe various part of a math
expression. For example, a presentation markup with content markup. But
it can also hold non-MathML content, like LaTeX form of the viewed
equation.
If this is your case, you have won. One program which commonly does
this is Pandoc, it annotates all equations with their LaTeX form, so
they can be copied very easily.
Selection of the equation should do the job, if not, saving the page as
txt could, or in worst case, examining the html code, search for
annotation tag.
Sadly I didn't see a common place, where equations would have this kind
of attachment, but I wasn't really looking for it, so you may find few,
where it will be available.

Best regards

Rastislav
V Štvrtok,  6. august 2020 o 15:19 +0200, Ishe Chinyoka via orca-list
napísal(a):
> Hi,
>
>
> I am finding Orca's handling of maths to my liking as it is able to
> say
> out all the maths expressions I come across. But I am failing to copy
> those formulas into some application, from Firefox. How do I
> accomplish
> such a thing as copying a maths expression?
>
> Currently, copying any expression yields the following string at the
> place where the expression should be: "[Math Processing Error]".
>
> TIA,