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 Bill Casselman's home page
 PiScript - a drawing tool for mathematicians
PiScript is a package
written by Bill Casselman in the programming language Python that interfaces in
a straightforward way to PostScript graphics commands.
It is designed for use by those who are interested in
producing graphics in mathematical exposition.
Its principal features are the directness of the interface
and the ease with which one can insert TEX text into figures.
New (as of July 21) is that PiScript
now seems to work on Windows machines. Thanks to Christophe K.
and Yair Goldberg
for help. Read the Manual for more remarks about this.
Downloads and installation
Documentation
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The manual for PiScript in .pdf and also in .ps format.
The .pdf file produced by .epstopdf is not quite accurate.
Compare the two versions of the middle diagram on p.13.
The official Acrobat from Adobe does better.
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My own notes on Type 1 fonts (.pdf)
I have spent a lot of time exploring fonts for this project,
although this work has barely shown up so far
in PiScript.
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PiScript command list
Examples
You will see the Python file that produced an image if you click on it
(assuming your browser is set to load .py files as text files,
which it should do for security reasons). If you have installed a
tool to view .eps files, you may also click on the
file names beneath the image.
The following are multi-page displays:
Major source code
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PiModule.py. This is the basic interface
to the classes in the files below. No serious work is done here.
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PiScript.py. The basic code,
including the class PiScript.
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PiScript3d.py. The 3D code,
including classes ConvexSurface, Face,
PiScript3d
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Cube.py - a sample polyhedron
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Sphere.py - a sample smooth surface
Other links
Other graphics packages for mathematicians
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Among all the packages mentioned here, this is closest to PiScript.
It handles TEX text in a similar fashion,
but does not follow the PostScript graphics model
very closely.
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PyScript
Similar in spirit as well as homonymous, but not a finished product
(and it is not clear to me that it is still an active project, either).
Like PYX, it does not follow PostScript as closely as I would like,
but it does have interesting TEX text placement.
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 Matplotlib (which is
used in SAGE)
This models itself on MatLab. Very powerful for big data plotting tasks.
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 The Processing project.
More art than mathematics, but the images its enthusiastic users
produce are often really beautiful.
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 IPE
By some of the authors of the book
Computational Geometry,
now in a third edition.
The book is one of the few about algorithms in computer graphics
that displays competent pictures. If the illustrations
in the book were written with IPE,
that's a good advertisement.
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 VRR
Like IPE, this is an interactive graphics tool,
rather than a programming tool. My impression is that neither
of them is useful for mathematicians
with little programming experience.
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 Xfig
A standard tool, used by multitudes.
Ugly, ugly, ugly. But interactive. Not to say, well prepared.
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PSTricks
This is one of several packages that make
pictures in a LaTeX environment, rather than TeX/LaTeX in a
graphics environment, which I find by far
preferable. It is in effect a LaTeX interface to
PostScript, and for that reason rather awkward as well
as limited. PostScript is a rather
interesting, even elegant, programming language, but LaTeX ... ?
(However, see the next item.)
I find it curious
that many graphics tools for mathematicians
often assume that the user does not want to do
any real programming. Mathematicians are notoriously
conservative about computers, so maybe
they have a point.
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 PGF & TikZ.
See also Kjell Fauske's home page.
These too are based on a LaTeX environment, but
they do much, much better than any others in this category.
For example, there is a 3D package using
Gene Ressler's Sketch,
which has many interesting features,
particularly the transparency effects.
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gnuplot
Very limited.
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Xy-pic
The favourite of many for setting commutative diagrams, which it does well.
Like two above, this is based on TeX.
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VfPlot
Seems designed just to plot vector fields. But it
does this in
a very sophisticated way.
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PythonPS
Another Python interface to PostScript programming
from the guy who brought you
the PostScript web server PSD-HTTPD.
Very spare.
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 MetaPost
An interface to PostScript in Don Knuth's graphics language
MetaFont, which he designed and used to make
the Computer Modern fonts that come with TEX.
By John Hobby, a former student of Knuth's.
Much if not all of Knuth's own graphics is
done with this tool
(as you can see from
Knuth's
preprints page, particularly the
color
figures for dancing links),
and it is therefore not to be scorned.
To my eye, however, the figures it produces have
a rather monotonous style, which indicates that
variety, although possible in principle,
is not easy to achieve.
See also the Wikipedia
entry on MetaPost.
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 Asymptote
From the home page:
... inspired by MetaPost, with a much cleaner, powerful C++-like
programming syntax and floating-point numerics. It
seems surprisingly powerful. Among other features,
it has an interesting and sophisticated
approach to keeping certain parts of a figure
at a fixed size while scaling the rest (which PiScript handles
with revert).
NOTE: I welcome
comments on any of these tools (mail to cass at math.ubc.ca).
It would be extremely useful even to assemble a table
comparing features such as
- TEX and text handling
- programming convenience
- coordinate changes
- library quality
- 3D capability
- control of graphics details
- speed of rendering
- ease of expansion
and whatever else distinguishes a good graphics program.
It should include
elementary samples of coding. But this
is not a job for just one person.
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