Robert Maier <rsm@math.arizona.edu> wrote the libplot/libplotter library
and the graphics programs graph, plot, tek2plot, and plotfont, beginning in
1995.  The old `GNU graphics' package (written by Rich Murphey
<rich@freebsd.org> in 1989-1991) served as a starting point, but the
plotutils package is an order of magnitude larger.  Probably none of the
code from the earlier package remains in libplot/libplotter or the graphics
programs.

spline and double were originally written by Rich.  They have been extended
by Robert, but some of Rich's code is still present.

Current versions of tek2plot are based on the Tektronix parser written by
Edward Moy <moy@parc.xerox.com> in the mid-1980's at Berkeley, which was
later included in the X11 distribution.

ode was written by Nick Tufillaro <nbt@reed.edu> in 1978-1994, and has been
somewhat modified and extended so as to merge it into the package.

Robert wrote the texinfo manual (the chapter on ode draws heavily on Nick's
original ode documentation, which dates in part to the late 1970s).

Most of the code in pic2plot (the scanner and parser code, in particular)
is taken from gpic, i.e. GNU pic.  gpic was written in 1989-1992 by 
James J. Clark <jjc@jclark.com> as part of groff, i.e. GNU troff.  
A libplot driver was added, to turn it into pic2plot.

The libxmi scan-conversion library is based on source files in the X Window
System distribution.  They were written in the mid-to-late 1980's by Brian
Kelleher, Joel McCormack, Todd Newman, Keith Packard, Robert Scheifler and
Ken Whaley, who worked for Digital Equipment Corp., MIT, and/or the X
Consortium.  Their contributions are copyright 1985-89 by the X Consortium.
See ./libxmi/README-X for X Consortium permission notices.