Re: graphics

[Vaughan Pratt <pratt@CS.Stanford.EDU>]

>My favorite method is to draw figures in xfig, then export the result as
>LaTeX picture code and edit the text to take advantage of LaTeX's
>text processing capabilities, fonts and special symbols.
>It would be quite suitable for flow chart graphics.
>D. Yetter

Xfig is pretty convenient, but one can get a tad impatient with xfig's
imprecision after a while.  The time it takes to drag a vertex into position
with acceptable precision tends in practice to be several times what it
takes to simply type that position in by hand if you can see right away
which lattice point it has to be.  If you're a Picasso in such things then
starting off with xfig isn't so bad, but if you're more of a Mondrian you
might prefer to work in Latex's picture environment from the get-go.

As with xypic, choosing a scale that makes the coordinates meaningful integers
helps a lot here, e.g. being able to coordinatize the vertices of a diamond
as (1,0), (0,1), (-1,0), (0,-1), or putting the inputs to an AND gate at
(0,1) and (0,3) and the output at (4,2), or putting the vertices of a Hasse
diagram at small lattice points.

The only other widely supported language I know that's expressive enough to
write a complete macro library in 20 lines for capabilities like flowcharts,
digital or analog circuits, and lattice diagrams and that interoperates
smoothly with Latex is PostScript.  That works too, the main downside
compared to programming directly in Latex's picture environment (for
those using pdflatex) is the external file needed in the use of epstopdf
plus includegraphics.  (I'm using both in the paper I'm currently working
on, mainly for fear of running out of Tex's memory with the more complex
figures.  Not that either are great programming languages per se, actually
they kind of suck in that regard, thank you Don, Leslie, John, and Chuck!)
The above comment about picking the right scale applies equally to Latex's
picture environment and PostScript.

When your diagrams are sufficiently like the ones that xypic, diagram.tex,
and diagrams.tex are designed for, those are pretty good too.  But they're
not really conceived of as programming languages, making their usefulness
inversely proportional to the distance between their kind of diagrams
and yours.

Vaughan Pratt