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

[Ishe Chinyoka <chinyoka consultant gmail com>]

Hi Rastislav,

Thanks for your helpful suggestions regarding the various technologies
used for mathematical presentation. Actually, I was trying to copy what
Orca was saying. As an example, the formula for the pooled estimate is
presented as:
(p1  + p2
)/(n1 + n2)
When I move my cursor to where the expression is, I do not have the
option to copy the formula. I tried pressing the context menu so as to
bring any other options for that formula, but failed. So what I ended up
doing was to literally type into my text editor what Orca was saying.
But I feel that this is an inefficient way to deal with lots of
formulas.

However, I think from what you are saying, I am getting a better idea of
what I have to do: dealing with the HTML source for the page. The only
setback I see in that is when I am participating in some MOOC courses
like at Coursera, where I have to answer a question after making some
calculations. In that situation, I may have no other way to review the
formula in time.

I will have to explore those other options like MathML and LaTeX. The
latter is what I often use for my daily work in preparing some material.
I find that LaTeX is the most accessible format out there when it comes
to maths. My issue right now is reading maths on Linux, which is now my
operating system of choice for the past two months.

Thanks once again.

Ishe




On Saturday,  8 August 2020, at 04:05, Rastislav Kiss via orca-list <orca-list gnome org> wrote:
> 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,
>
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-- 
Ishe Chinyoka
Mobile: +263-77-396-5354
Website: https://www.chinyoka.com/