RF21 for Windows is a scientific calculator, plotter, programming and numeric system in one. It allows for permanent installation of a user's own commented functions and libraries. Such user functions may have one or several arguments and values. Works as an archive at the same time, with integrated searchable database, to let you find and reuse materials created years ago. Each function self-reassembles when its name is called, autonomously searching the libraries for all components needed. Predefined functions include gamma, zeta, psi and Bessel functions, error integral, cumulative Binomial distribution and more. On top of these and the user libraries, the program's numeric and plotting capabilities can be used, including: Numeric derivation and integration, Monte Carlo simulations, linear equations, matrix inversion and eigenvalues, nonlinear equation systems, n-dimensional function minimizer (Dennis & Schnabel method), Runge Kutta method for (systems of) differential equations, accelerated summation of series. Fraction reckognizer. Fast screenplots and an environment for designing printable plots, which may as well be exported to -.GIF and -.BMP files. Ample support for both simple and parametric plots, composition of several curves into one picture, drawing of directional or vector fields. Comes with standard libraries covering areas of science and mathematics. Some 200 standard functions, see author's homepage for a systematic reference of these.