octave-ann is a set of bindings that allow one to use the ANN library from within Octave in a natural way. The ANN (Approximate Nearest Neighbor) library has some nice data structures and algorithms for computing exact or approximate nearest neighbors on an arbitrarily high-dimensional point set.
Big Fraction is a Java class that represents an immutable fraction, as held in a numerator and denominator. Calculations may be performed on this fraction, but the value is always held as a numerator/denominator pair. Therefore, no precision is lost. The fraction may be top-heavy, but is reduced when printed. The value can be converted into floats if desired, although precision will invariably be lost, and some large fractions (such as calculations for pi) can not be converted if the values of BigInteger exceed the range capable of floats.
Mathnium is a program for interactive numerical computations. With its comprehensive library of functions for a variety of problems in applied mathematics, and with its facilities for the definition and manipulation of arrays of numbers as basic data objects, Mathnium allows you to solve numerical problems rather painlessly and without a great deal of programming effort. Mathnium may also be used as a programming language to implement numerical algorithms in a concise manner which usually is very close to the mathematical description of the algorithms.
MonoDecrypt uses pattern matching and its knowledge about character frequencies in order to decrypt messages encoded with a monoalphabetic substitution cipher. MonoDecrypt can decrypt texts of any language, as long as it has sufficient information about the language. Depending on the information you give it, the tool decrypts about 50%-100% on its own. Then you can decrypt the remaining data by filling the gaps or correcting bad guesses. MonoDecrypt can also encrypt texts using monoalphabetic substitution.