On 5/21/2014 8:16 AM, Philipp Gesang wrote:
http://www.informit.com/articles/article.aspx?p=2213858&WT.mc_id=Author_Knuth_20Questions
Quote:
“The people at MSP wrote special software that converts my TeX
source text into suitable input to other software that
creates pdf files.”
I wonder why using a TeX engine capable of producing PDF output
directly wasn’t an option.
Ok, I think this is what sums it:
quote: "My principal goal was to make the books easily searchable—and
that's a much more challenging problem than it seems, if you want to do
it right. Secondarily, I wanted to let readers easily click on the
number of any exercise or equation or illustration or table or
algorithm, etc., and to jump to that exercise; also to jump readily
between an exercise and its answer."
(1) The interactive bit is rather trivial: cross references, tocs and
indices, linking answers and questions, are already generated so there
one only needs to add some hyperlinking code (maybe some additional
housekeeping if backlinks or in the case of indices linked backlinks are
supported but it is probably kept simple in order not to spoil the look
and feel.)
(2) The searching might be more complex as traditional 8 bit fonts are
used in plain tex, so there is some tounicode magic needed (not too hard
either, mostly housekeeping and careful checking) ... math can be
somewhat complex there as not all is copyable, given that it's needed,
but on the other hand, searching is also non trivial: does a reader
search for "unicode symbol math italic i" or for just an "i"? Copying
math demands a proper tounicode, but I bet no viewer can search for both
kind of tagging at the same time (math alphabet stuff). Searching
regular text of course is no issue.
(3) The question is: has more been added than just basic access as in
books? Crosslinking books and so?
So, no rocket science, mostly careful keeping the original (not
interfering with breaks and so) so that is probably where most of the
work went into. If pdftex was used, one thing to keep in mind is that
adding whatsits can interfere sometimes. This can be avoided by luatex
but then one has to accept the fact that the output can differ (no lig
recomposition), although that can be checked by diffing pdf's and making
local exceptions. A nice challenge: kind of making an electronic
facsimile i.e. don't touch (spoil) the original.
Hans
ps. An interesting audience, those asking the questions.
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Hans Hagen | PRAGMA ADE
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