FFTW is a fast C FFT library. It includes complex, real, symmetric, multidimensional, and parallel transforms, and can handle arbitrary array sizes efficiently.It is typically faster than other freely available FFT implementations, and is even competitive with vendor-tuned libraries (benchmarks are available at the homepage). To achieve this performance, it uses novel code generation and runtime self optimization techniques (along with many other tricks).
BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, and image and signal-processing tools.
JGraph is a free, mature, and robust Java diagramming library. It contains all the graph visualization, layout, and interaction functionality you might expect in a graph library, including multiple views, layering, zoom, drag and drop, undo, automatic expanding and collapsing, routing, and layouts. You can create workflow editors, BPMN, CAD tools, network diagrams, database visualization tools, and more. It is fully documented, including examples, and has an active support community.
Class Library for Numbers (CLN) is a library for computations with all kinds of numbers. Its rich set of number classes includes integers, rational numbers, floating-point numbers, complex numbers, modular integers, and univariate polynomials. It implements elementary functions (also with unlimited precision), logical functions, and transcendental functions. It is designed for memory and speed efficiency as well as interoperability.
Sequoia provides high availability and performance scalability for databases. It is is the continuation of the C-JDBC project. It provides transparent database clustering (partitioning, replication, etc.). It works with any Java application without code modification and with any database engine. It has been successfully tested with Tomcat, JBoss, JOnAS, WebSphere, MySQL, PostgreSQL, Apache Derby, HSQLDB, SAP DB, Oracle, DB2, Sybase, MS SQL Server, Firebird, and more.
GRASS (the Geographic Resources Analysis Support System) is a software raster- and vector-based GIS (Geographic Information System), image processing system, graphics production system, and spatial modeling system. It contains many modules for raster data manipulation, vector data manipulation, rendering images on the monitor or paper, multispectral image geocoding and processing, point data management and general data management. It also has tools for interfacing with digitizers, scanners, and the PostgreSQL, DBF, and ODBC connected databases. GRASS operates on all common operating systems.
The ATLAS (Automatically Tuned Linear Algebra Software) project is an ongoing research effort focusing on applying empirical techniques in order to provide portable performance. It provides C and Fortran77 interfaces to a portably efficient BLAS implementation, as well as a few routines from LAPACK.