SlackBuildsOrg/academic/gri

Gri is a language for scientific graphics applications.  By 'language'
I mean that it is a command-driven application, as opposed to a
click/point application.  It is analogous to latex or tex, and shares
the property that extensive power is the reward for tolerating a
learning curve.  Gri output is in PostScript, suitable for 
incorporation in documents prepared by various text processors.

Gri can make x-y graphs, contour-graphs, and image graphs.  In
addition to high-level capabilities, it has enough low-level
capabilities to allow users to achieve a high degree of customization.
Control is extended to all aspects of drawing, including
line widths, colors, and fonts.  Text includes a subset of the tex
language for letters and mathematical symbols in labels.