IIR is a C++ library that implements fast IIR filters: bandpass, bandstop, lowpass, and highpass. These can be designed using popular analogue filter functions such as Butterworth, Bessel, Chebyshev, Elliptic, Legendre, and pole placement. Creation of a complete filter requires only a single command and filtering is performed with a single function taking a sample and returning its result instantly. The library is template-based and avoids new/mallocs throughout. This library has been adapted form Vinnie Falco's original work and has been converted to run on Unix systems and turned into a realtime causal filter.
xmlsd is a library that wraps expat in order to simplify XML use in C programs as well as adding rigid rules to an XML structure. The idea is to have XML structures that can be passed over the network with implicit parameter verification. This in turn enables back and forth chattering between applications.
SHTns is a high-performance Spherical Harmonic Transform library. It was designed for numerical simulation (fluid flows, mhd, etc.) in spherical geometries, but can be used for any kind of problem involving scalar or vector spherical harmonics. It is very fast, thanks to careful vectorization and runtime tuning. It supports multi-threaded transforms via OpenMP. It features scalar and vector transforms, synthesis and analysis, and flexible truncation and normalization. A Python interface is included.