Libplot
From The GNU Plotting Utilities:
GNU libplot is a free function library for drawing two-dimensional vector graphics. It can produce smooth, double-buffered animations for the X Window System, and can export files in many graphics file formats. It is `device-independent’ in the sense that its API (application programming interface) is to a large extent independent of the display type or output format.
GNU Libplot library is a part of GNU Plotutils package.
Ch
From The Ch Language Environment—SDK User’s Guide, version 5.1 [PDF]
Ch is an embeddable C/C++ interpreter. Ch supports all features in the ISO 1990 C standard, most new features in the latest ISO C99 standard including coplex and variable length arrays, lasses in POSIX, C++, Win32, X/Motif, OpenGL, GTG+, ODBC, WinSock, very high-level shell programming, corss-platform internet computing in safe Ch, computational arrays for linear algebra and matrix computations, high-level 2D/3D plotting and numerical computing such as differential equation solving, integration, Fourier analysis. Ch can also be used as a login Unix command shell and for high-level scripting such as shell programming to automate tasks and common gateway interface in a Web server in both unix and Windows.
ChLibplot
ChLibplot is the Ch interface to Libplot library. It provides access to most of the Libplot library features so programs using it can be conveniently executed in Ch space.