The Date::Calc package consists of a (pure-Perl) wrapper which either loads Date::Calc::XS (a separate implementation in C and XS) or Date::Calc::PP (a pure-Perl implementation which is part of the Date::Calc package). The Date::Calc::XS and Date::Calc::PP modules perform all kinds of date calculations based on the Gregorian calendar (the one used in all Western countries today), according to relevant norms and standards: ISO/R 2015-1971, DIN 1355 and, to some extent, ISO 8601 (where applicable). The package is designed as an efficient toolbox, not a bulky ready-made application. It provides extensive documentation and examples of use, multi-language support, and special functions for business needs.
The Date::Pcalc Perl module is a direct translation of Steffen Beyer's excellent Date::Calc module from a combination of C and Perl to Perl only. The Perl module does all kinds of date calculations based on the Gregorian calendar (the one used in all western countries today), thereby complying with all relevant norms and standards: ISO/R 2015-1971, DIN 1355 and, to some extent, ISO 8601 (where applicable).
distributed.net is a loosely knit group of computer users from all of the world that is taking up challenges requiring lots of computing power (most notably the RC5, DES, and OGR cracking contests). It is simple to participate in the challenges by downloading and running their client software (which uses idle CPU time to complete its tasks).
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).
FXT is a C++ library containing code for various fast orthogonal transforms (Fourier-, Hartley-, Walsh-, Haar-, Wavelet-transform) and convolution. It contains a large collection of low (bit) level routines and combinatorial algorithms (permutations, combinations, necklaces, de Bruijn sequences). Number theoretic transforms and modular arithmetics are implemented. Operations on binary polynomials and arithmetics in finite fields GF(2^n) are included. The package contains more than 150 short programs that demonstrate how to use its functionality.