[texhax] extracting math from pdf file

Philip Taylor (Webmaster, Ret'd) P.Taylor at Rhul.Ac.Uk
Sun Dec 5 23:05:14 CET 2010

Benjamin Sambale wrote:
> Dear forum,
> consider the following code:
> \documentclass{minimal}
> \begin{document}
> $\ne$
> \end{document}
> I compiled this code using pdflatex (TeX Live 2010). If I try to copy
> the \ne-symbol in the corresponding pdf-file with the mouse cursor, I
> get an equality-sgin (=) instead. I only tried this with evince as pdf
> viewer, but I suspect that the behavior is similar for other viewers.

> I'm very grateful for any ideas.

Well.  Acrobat Reader X shews the fonts as embedded subsets of
CMR10 & CMSY10.  The <= will undoubtedly come from CMSY10.  But where
it will lie within the embedded subset is anyone's guess.  Having
copied it with the mouse cursor, what will you have on the clipboard ?
A font/glyph pair, or just an ASCII or Unicode character.  I don't
know.  But even if it were a font/glyph pair, do you have any
applications that can display characters from CMSY10 ?  I don't.
(Unless CMSY10 is already embedded in the document, that is).
So, to be honest, I don't think that what you are hoping for
is feasible.  But I might be wrong :-)

Philip Taylor

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