The Racket repository
![]() Note: With this refactoring, `math/utils' no longer depends on `rackunit'. * (flexp2 x) computes (flexpt 2.0 x) but in about 1/3 the time for integer `x' using a lookup table. Written for exact argument reduction in `fllog2' after discovering that (flexpt 2.0 x) was the main performance bottleneck. * (fllog2 x) computes (/ (fllog x) (fllog 2.0)) with near perfect accuracy. Invented an algorithm to compute it with at least 8 extra bits before final rounding; quite pleased with the result. Needed `fllog2' to ensure (fllogb 2.0 x) would be exact when `x' is a power of two. * (fllogb b x) computes (/ (fllog x) (fllog b)) with better accuracy, and also handles limit values in a way that's consistent with the mathematical limits. When those are ambiguous, it's consistent with `flexpt', which follows IEEE 754 and C99. Otherwise returns +nan.0. See docs for details. * `bflogb' is currently just for testing `fllogb'. * Refactored FPU testing and documented it. So far, the only documented way to do it is by calling `test-floating-point', which runs a comprehensive deterministic+randomized suite of tests and returns a list representing failed tests. I'll document individual tests after I document flonum expansions and result/error functions like `fl+/error'. * Added `fllog2' and `fllogb' to the flonum tests. |
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README |
The Racket Programming Language =============================== Instructions for building Racket from source are in src/README. The main executables in this package: * DrRacket: Racket's integrated development environment (start here!). * racket: command-line tool for running Racket programs. * raco: command-line tool for compilation, documentation, and more. More Information ---------------- For Racket documentation, use DrRacket's `Help' menu, run the `Racket Documentation' application (Windows or Mac OS X), or run `raco docs' from a command line. Visit us at http://racket-lang.org/ for more Racket resources. License ------- Racket Copyright (c) 2010-2013 PLT Scheme Inc. Racket is distributed under the GNU Lesser General Public License (LGPL). This means that you can link Racket into proprietary applications, provided you follow the rules stated in the LGPL. You can also modify Racket; if you distribute a modified version, you must distribute it under the terms of the LGPL, which in particular means that you must release the source code for the modified software. See doc/release-notes/COPYING.txt for more information.