linSmith is a Smith charting program. Users can enter either discrete components or transmission lines, see the results on screen, and/or generate Postscript output. Component values can be changed numerically or using scrollbars. Problems can be solved on-screen, and high-quality Postscript can be output for publication.
Asymptote is a powerful descriptive 2D and 3D vector graphics language for technical drawing, inspired by MetaPost but with an improved C++-like syntax. It provides for figures the same high-quality level of typesetting that LaTeX does for scientific text. Asymptote is a programming language as opposed to just a graphics program. It can exploit the best features of script (command-driven) and graphical user interface (GUI) methods. High-level graphics commands are implemented in the language itself, allowing them to be easily tailored to specific applications.
Genius is an arbitrary precision integer and multiple precision floating point calculator. It includes its own programming language similar in some aspects to C, bc, or Pascal. It can deal with rational numbers and complex numbers. It has matrix support as well. It uses the gmp library so it is very fast for calculations of large numbers. It has a command line and a GNOME interface. The GNOME interface supports plotting functions and 3D surfaces.
jHepWork (jWork) is an environment for scientific computation, data analysis, and data visualization for scientists, engineers, and students. The program is fully multi-platform (written in Java). Programs can be written in the Java, Jython/Python, and BeanShell scripting languages. Matlab/Octave is supported for symbolic calculations. The program can be used to display data and functions in D and 3D. It comes with a friendly IDE and a code assist.
BALLView is an extensible viewer for bio-molecular structures. It provides all standard models and offers rich functionality for molecular modeling and simulation, including molecular mechanics methods (AMBER, CHARMM, and MMFF94 force fields), continuum electrostatics methods employing a Finite-Difference Poisson Boltzmann solver, secondary structure calculation, molecular editing and docking. Since BALLView is based on BALL (the Biochemical ALgorithms Library), it is easily extensible on the level of C++ code. In addition, it provides a Python interface with Integrated Development Environment features to allow interactive rapid prototyping.
Python Mesh Viewer is a very basic tool to display and play with 3D models. You can either construct them in the code (by defining points, triangles, and quads) or load them from a file. Currently, the only file format supported is the ".mesh" format from the closed source software medit. The rendering is done with absolutely no hardware acceleration (no OpenGL).
Scilab is a numerical computation system similiar to Matlab or Simulink. Scilab includes hundreds of mathematical functions, and programs from various languages (such as C or Fortran) can be added interactively. It has sophisticated data structures (including lists, polynomials, rational functions, and linear systems), an interpreter, and a high-level programming language. Scilab has been designed to be an open system where the user can define new data types and operations on these data types by using overloading. A number of toolboxes are available with the system.
The Chemistry Development Kit (CDK) is a library of Java classes for chemo-, bioinformatics, computational chemistry, and chemometrics. It provides important algorithms like substructure search, SMILES, Gasteiger charges, QSAR descriptor calculation, 3D structure generation, 2D layout and rendering, many IO formats, atom typing, and more.