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Boost.Multiprecision is a C++ library that provides integer, rational, floating-point, complex and interval number typeshaving more range and precision than the language's ordinary built-in types.

Language adherence:

• Boost.Multiprecision requires a compliant C++14 compiler.
• It is compatible with C++14, 17, 20, 23 and beyond.

The big number types inBoost.Multiprecision can be used with a wide selection of basicmathematical operations, elementary transcendental functions as well as the functions in Boost.Math. The Multiprecision types canalso interoperate with the built-in types in C++ using clearly defined conversion rules. This allowsBoost.Multiprecision to beused for all kinds of mathematical calculations involving integer, rational and floating-point types requiring extended range and precision.

Multiprecision consists of a generic interface to the mathematics of large numbers as well as a selection of big number back ends, withsupport for integer, rational and floating-point types.Boost.Multiprecision provides a selection of back ends provided off-the-rack inincluding interfaces to GMP, MPFR, MPIR, TomMath as well as its own collection of Boost-licensed, header-only back ends for integers,rationals, floats and complex. In addition, user-defined back ends can be created and used with the interface of Multiprecision,provided the class implementation adheres to the necessary concepts.

Depending upon the number type, precision may be arbitrarily large (limited only by available memory), fixed at compile time(for example$50$ or$100$ decimal digits), or a variable controlled at run-time by member functions.The types are expression-template-enabled by default. This usually provides better performance than naive user-defined types.If not needed, expression templates can be disabled when configuring thenumber type with its backend.

The full documentation is available onboost.org.

In the following example, we use Multiprecision's Boost-licensed binaryfloating-point backend typecpp_bin_float to compute${\sim}100$ decimal digits of

$$\sqrt{\pi} = \Gamma \left( \frac{1}{2} \right)~{\approx}~1.772453850905516027298{\ldots}\text{,}$$

where we also observe that Multiprecision can seemlesly interoperate withBoost.Math.

#include<iomanip>#include<iostream>#include<sstream>#include<boost/multiprecision/cpp_bin_float.hpp>#include<boost/math/special_functions/gamma.hpp>automain() -> int{using big_float_type = boost::multiprecision::cpp_bin_float_100;const big_float_type sqrt_pi {sqrt(boost::math::constants::pi<big_float_type>()) };const big_float_type half {big_float_type(1) /2 };const big_float_type gamma_half {boost::math::tgamma(half) };   std::stringstream strm { };  strm <<std::setprecision(std::numeric_limits<big_float_type>::digits10) <<"sqrt_pi   :" << sqrt_pi <<'\n';  strm <<std::setprecision(std::numeric_limits<big_float_type>::digits10) <<"gamma_half:" << gamma_half;  std::cout << strm.str() << std::endl;}

DefiningBOOST_MP_STANDALONE allowsBoost.Multiprecisionto be used with the only dependency beingBoost.Config.

Ourpackage on this pagealready includes a copy of Boost.Config so no other downloads are required.Some functionality is reduced in this mode.A static_assert message will alert you if a particular feature has been disabled by standalone mode.Boost.Math standalone mode is compatiable,and recommended if special functions are required for the floating point types.

Bugs and feature requests can be reported through theGitub issue tracker(seeopen issues andclosed issues).

You can submit your changes through apull request.

There is no mailing-list specific toBoost Multiprecision,although you can use the general-purpose Boostmailing-listusing the tag [multiprecision].

Clone the whole boost project, which includes the individual Boost projects as submodules(see boost+git doc):

  git clone https://github.com/boostorg/boostcd boost  git submodule update --init

The Boost Multiprecision Library is located inlibs/multiprecision/.

First, build theb2 engine by runningbootstrap.sh in the root of the boost directory. This will generateb2 configuration inproject-config.jam.

  ./bootstrap.sh

Now make sure you are inlibs/multiprecision/test. You can either run all the tests listed inJamfile.v2 or run a single test:

  ../../../b2<- run all tests  ../../../b2 test_complex<- singletest