[pdftex] Re: eps files

[Nelson H. F. Beebe]

Sam Tygier asks today:

>>  what the reason is for pdflatex not being able to eps files directly.

The reason is simple: PostScript is a full-blown programming language,
and PDF is a page markup language that is devoid of programming
language constructs, like variables, conditionals, loops, and function
calls.  Think of PDF as a subset of PostScript with no
programmability, one-character command names, and some extensions like
a complex binary format (ASCII is possible too, but uncommon), and
support for transparency and embedded objects (e.g., audio, video, and
other PDF objects), and inter- and intra-document links (like Web
URLs).

If pdflatex were to permit EPS file inclusion, it would have to
convert them somehow to PDF, a job best left for external programs.
As evidence of this remark, the TeX and Metafont programs are each
about 20K lines of Pascal, while the latest ghostscript release is
almost 800K lines of C.

The \includegraphics{} command in the LaTeX graphicx package is best
used by leaving off file extensions: then it can supply .eps or .pdf,
depending on whether ordinary LaTeX, or PDFLaTeX, is being used.

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