THE GNU MP LIBRARY
GNU MP is a library for arbitrary precision arithmetic, operating on signed
integers, rational numbers, and floating point numbers. It has a rich set of
functions, and the functions have a regular interface.
GNU MP is designed to be as fast as possible, both for small operands and huge
operands. The speed is achieved by using fullwords as the basic arithmetic
type, by using fast algorithms, with carefully optimized assembly code for the
most common inner loops for lots of CPUs, and by a general emphasis on speed
(instead of simplicity or elegance).
GNU MP is believed to be faster than any other similar library. Its advantage
increases with operand sizes for certain operations, since GNU MP in many
cases has asymptotically faster algorithms.
OVERVIEW OF GNU MP
There are five classes of functions in GNU MP.
1. Signed integer arithmetic functions (mpz). These functions are intended
to be easy to use, with their regular interface. The associated type is
`mpz_t’.
2. Rational arithmetic functions (mpq). For now, just a small set of
functions necessary for basic rational arithmetics. The associated type
is `mpq_t’.
3. Floating-point arithmetic functions (mpf). If the C type `double’
doesn’t give enough precision for your application, declare your
variables as `mpf_t’ instead, set the precision to any number desired,
and call the functions in the mpf class for the arithmetic operations.
4. Positive-integer, hard-to-use, very low overhead functions are in the
mpn class. No memory management is performed. The caller must ensure
enough space is available for the results. The set of functions is not
regular, nor is the calling interface. These functions accept input
arguments in the form of pairs consisting of a pointer to the least
significant word, and an integral size telling how many limbs (= words)
the pointer points to.
Almost all calculations, in the entire package, are made by calling these
low-level functions.
5. Berkeley MP compatible functions.
To use these functions, include the file "mp.h". You can test if you are
using the GNU version by testing if the symbol __GNU_MP__ is defined.
For more information on how to use GNU MP, please refer to the documentation.
It is composed from the file doc/gmp.texi, and can be displayed on the screen
or printed. How to do that, as well how to build the library, is described in
the INSTALL file in this directory.
转载请注明：在路上 » what is GMP in Linux