What is PLplot?

PLplot is relatively small, portable, freely distributable plotting
library, that is rich enough to satisfy most users.  It has a wide
range of plot types including line (linear, log), contour, 3D, fill.
It also supports unicode (UTF-8) text so that plots can include a very
large range of mathematical symbols and be labeled in every human
language.  The package is designed to make it easy to quickly get
graphical output; only a handful of function calls are typically
required. For more advanced use, virtually all aspects of plotting are
configurable.


Why and when did PLplot come to be?

PLplot was originally developed by Sze Tan of the University of Auckland 
in Fortran-77 (in 1986). Many of the underlying concepts used in the 
PLplot package are based on ideas used in Tim Pearson's PGPLOT package.
Sze Tan writes:

    I'm rather amazed how far PLPLOT has traveled given its origins etc. I
    first used PGPLOT on the Starlink VAX computers while I was a graduate
    student at the Mullard Radio Astronomy Observatory in Cambridge from
    1983-1987. At the beginning of 1986, I was to give a seminar within the
    department at which I wanted to have a computer graphics demonstration on
    an IBM PC which was connected to a completely non-standard graphics
    card. Having about a week to do this and not having any drivers for the
    card, I started from the back end and designed PLPLOT to be such that one
    only needed to be able to draw a line or a dot on the screen in order to
    do arbitrary graphics. The application programmer's interface was made as
    similar as possible to PGPLOT so that I could easily port my programs from
    the VAX to the PC. The kernel of PLPLOT was modeled on PGPLOT but the code
    is not derived from it.

Then Tony Richardson ported it to the Commodore Amiga, rewriting in C with
additional improvements.

While doing a post-doc fellowship in Japan Maurice LeBrun needed a free 
scientific graphics library for his plasma simulation code and came across 
PLplot on the Amiga "Fish disks" (disk 222).  Maurice ported it back to 
several varieties of Unix and took over maintenance from Tony. After 
returning to the Institute of Fusion Studies at University of Texas Maurice 
continued to develop the package, with Geoff Furnish joining him as a
co-developer. In the early 90s's the new contributions were released under 
the LGPL.

When Maurice left UT in '95 Geoff became sole maintainer for some years, 
and was responsible for getting it up at Sourceforge in the earliest days 
of that site's existence.  That made it easier to add collaborators & such, 
and starting with Alan Irwin & Rafael Laboissiere the core team gradually 
came to be.


In which [language(s)|platform(s)] is PLplot developed?

PLplot is developed in primarily C, with language bindings for Ada, C++, 
D, Fortran, Java, Lua, Perl, Python, OCaml, Octave and Tcl/Tk. Every effort 
is made to support the Linux, OS-X, and Windows platforms.

Also answering the question from the human language perspective,
PLplot is developed exclusively in English.  However, it has both a
fine mathematical reputation and international reputation because of
its complete support for unicode (UTF-8) for all text strings and
symbols that are plotted by our modern device drivers.  We presume
this is one of the reasons why PLplot usage is spread between 100
different countries (see below).


Does PLplot have sponsors (private, academic, other)?

Virtually all of our developers have been unpaid volunteers.  The
exception has been a recent important development contribution from
the Cluster Science Centre QSAS team, Imperial College, London


How are the sponsors supporting the project?

QSAS donated the original version of the qt device driver along with ~two
months of developer time to help with its integration into PLplot.


How many users do you estimate PLplot has?

16 000 binary and source users actively use it divided between Linux
(73 per cent), Windows (22 per cent), and OS X (5 per cent).  Users
are widely spread between about 100 countries with US users leading
the pack but only with a 22 per cent share and with 18 countries in
total having more than a 1 per cent share each.

These estimates are necessarily extremely approximate, but here is how
we arrived at these figures.  Statistics at
http://qa.debian.org/popcon.php?package=iceweasel show roughly half of
Debian users are desktop users.  Thus, multiplying the popularity
contest statistics at http://qa.debian.org/popcon.php?package=plplot
by a factor of two to obtain the desktop share for PLplot, 0.2 per
cent of Debian desktop users, use it regularly.  Furthermore make the
(conservative?)  assumption there are 5 million Linux desktop users in
the world with similar needs to Debian desktop users.  Combining the
above estimates leads to an estimate of 10 000 Linux desktop users who
use a binary version of PLplot regularly.

An additional type of PLplot user downloads and builds PLplot for
themselves rather than using a binary package.  The result from
http://sourceforge.net/projects/plplot/files/plplot/5.9.7%20Source/stats/timeline?dates=2009-10-01+to+2011-07-27
is ~3500 Windows downloads, ~1700 Linux downloads, ~800 Mac OS X
downloads, and ~500 downloads where the OS could not be identified.
The total downloads for all OS's were ~6500.  Presumably most of these
downloaders (say 6000 of them) will build PLplot for themselves and
use it regularly.  When the unknown OS is split between the various
OS's appropriately, and those splits adjusted for
the 10 000 Linux binary package users we arrive at the final estimate
given above.  

Note the above summary of the country statistics comes directly from
SourceForge PLplot source download statistics site so these splits are
likely distorted by lack of similar evidence from the binary package
users of PLplot.


Do you know where PLplot is used (corporations, universities, other)?

No, although we assume it is used mostly for scientific plotting.


How many team members does PLplot have?  (You can list their names)

There are 10 PLplot developers who currently have write access to our
subversion repository.  Their names are Alan W. Irwin, Andrew Ross,
Arjen Markus, Geoffrey Furnish, Hazen Babcock, Hezekiah M. Carty, Doug
Hunt, Jerry Bauck, Maurice LeBrun, and Werner Smekal.  For more information
on the work of our current developers and historical developers see
PLplot see http://www.ohloh.net/p/plplot/contributors.


In what areas of PLplot development do you currently need help?

This project is fairly mature, so we are primarily looking for help in
documentation and testing on various platforms, particularly
windows. Bug reports are also appreciated.


How can people get involved with PLplot?

The best way to start is by submitting suggestions and patches to the
mailing list. Users who seem particularly enthusiastic and who have
a history of contributions are often added to the project as developers
with subversion repository write access.


What features are in the roadmap?

The PLplot project does not have a formal roadmap. Development
operates primarily in a reactive mode, bugs are fixed as users 
discover them and features are added on request (if there is a 
consensus among the developers that the feature seems like a
reasonable addition).

