Boost Library를 이용하여 임의의 정밀도를 갖는 부동소수점수 계산하기

 

Boost Library 1.75.0 을 설치하고

Visual Studio 2019 의 명령행 컴파일러 cl 로 컴파일하였다.

컴파일하기 전에 미리 환경변수 BOOST_LIB_PATH 와 MPIR_LIB_PATH 를 각각

Boost Library 와 MPIR Library 가 있는 경로로 설정해 놓아야 한다.

 

/*
 * Filename: CalculateAreaOfDiskWithBoosLibrary.cpp
 *
 *       Purpose: Test floating point numbers of arbitrary precision.
 *
 * Compile: cl CalculateAreaOfDiskWithBoosLibrary.cpp /I%BOOST_LIB_PATH% /I%MPIR_LIB_PATH% /EHsc /utf-8 MPIR_LIB_PATHmpir.lib
 * Execute: CalculateAreaOfDiskWithBoosLibrary
 *
 * Date: 2021.03.29
 * Revised Author: pkim ((AT)) scripts ((DOT)) pe ((DOT)) kr 
 *
 * See: www.boost.org/doc/libs/1_56_0/libs/multiprecision/doc/html/boost_multiprecision/tut/floats/gmp_float.html
 */
 
#include<iostream>
#include <boost/multiprecision/cpp_bin_float.hpp>
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/math/constants/constants.hpp>

using boost::multiprecision::cpp_dec_float_50;
using boost::multiprecision::cpp_dec_float_100;
using boost::multiprecision::cpp_dec_float;
using boost::multiprecision::cpp_bin_float_quad;

#include <boost/multiprecision/gmp.hpp>
using namespace boost::multiprecision;

typedef boost::multiprecision::number<boost::multiprecision::cpp_dec_float<40> > flp_type_dec_40;
typedef boost::multiprecision::number<boost::multiprecision::cpp_dec_float<49> > flp_type_dec_49;
typedef boost::multiprecision::number<boost::multiprecision::cpp_dec_float<99> > flp_type_dec_99;
typedef boost::multiprecision::number<boost::multiprecision::cpp_dec_float<101> > flp_type_dec_101;


using namespace std;

template<typename T>
inline T area_of_a_circle(T r)
{
    // pi represent predefined constant having value
    // 3.1415926535897932384...
    using boost::math::constants::pi;
    return pi<T>() * r * r;
}



void testFloatNumbers()
{
	float radius_f = 123.0/ 100;
	float area_f = area_of_a_circle(radius_f);

	double radius_d = 123.0 / 100;
	double area_d = area_of_a_circle(radius_d);

	cpp_dec_float_50 r_mp = 123.0 / 100;
	cpp_dec_float_50 area_mp = area_of_a_circle(r_mp);

	cpp_dec_float_100  r_100 = 123.0 / 100;
	cpp_dec_float_100 area_100 = area_of_a_circle(r_100);


	cpp_bin_float_quad  r_quad= 123.0 / 100;
	cpp_bin_float_quad area_quad = area_of_a_circle(r_quad);


	flp_type_dec_40  r_40 = 123.0 / 100;
	flp_type_dec_40 area_40 = area_of_a_circle(r_40);


	flp_type_dec_49  r_49 = 123.0 / 100;
	flp_type_dec_49 area_49 = area_of_a_circle(r_49);


	flp_type_dec_99  r_99 = 123.0 / 100;
	flp_type_dec_99 area_99 = area_of_a_circle(r_99);


	flp_type_dec_101  r_101 = 123.0 / 100;
	flp_type_dec_101 area_101 = area_of_a_circle(r_101);


      using boost::math::constants::pi;
      cout << "Let be given a circle with radius, r = " << radius_d << endl;
      cout << "Calculate the area of the given circle,\n        Area = PI*r^2 = " << pi<double>() << "*" << radius_d << "^2 = " << pi<double>() << "*" << (radius_d * radius_d) << ",\nin various precisions." << endl << endl;;

	// numeric_limits::digits10 represent the number
	// of decimal digits that can be held of particular
	// data type without any loss.
	
	// Area by using float data type
	cout << " Float: "
		<< setprecision(numeric_limits<float>::digits10)
		<< area_f << endl;

	// Area by using double data type
	cout << "Double: "
		<<setprecision(numeric_limits<double>::digits10)
		<< area_d << endl;


	// Area by using Boost 40 precision Multiprecision
	cout << "Boost Multiprecision  (40 digits): "
		<< setprecision(numeric_limits<flp_type_dec_40>::digits10)
		<< area_49 << endl;

	// Area by using Boost 49 precision Multiprecision
	cout << "Boost Multiprecision  (49 digits): "
		<< setprecision(numeric_limits<flp_type_dec_49>::digits10)
		<< area_49 << endl;

	// Area by using Boost 50 precision Multiprecision
	cout << "Boost Multiprecision  (50 digits): "
		<< setprecision(numeric_limits<cpp_dec_float_50>::digits10)
		<< area_mp << endl;

	// Area by using Boost 99 precision Multiprecision
	cout << "Boost Multiprecision  (99 digits): "
		<< setprecision(numeric_limits<flp_type_dec_99>::digits10)
		<< area_99 << endl;

	// Area by using Boost 100 precidion Multiprecision
	cout << "Boost Multiprecision (100 digits): "
		<< setprecision(numeric_limits<cpp_dec_float_100>::digits10)
		<< area_100 << endl;

	// Area by using Boost 101 precision Multiprecision
	cout << "Boost Multiprecision (101 digits): "
		<< setprecision(numeric_limits<flp_type_dec_101>::digits10)
		<< area_100 << endl;

	// Area by using Boost Quaduple Multiprecision
	cout << "Boost Multiprecision  (Quadruple): "
		<< setprecision(numeric_limits<cpp_bin_float_quad>::digits10)
		<< area_quad << endl;
}


int main()
{ 
	testFloatNumbers();
	return 0;
}


/*
Output:
-------------------------------------------
Let be given a circle with radius, r = 1.23
Calculate the area of the given circle,
        Area = PI*r^2 = 3.14159*1.23^2 = 3.14159*1.5129,
in various precisions.

 Float: 4.75292
Double: 4.752915525616
Boost Multiprecision  (40 digits): 4.752915525615998053187629092943809341311
Boost Multiprecision  (49 digits): 4.752915525615998053187629092943809341310825398145
Boost Multiprecision  (50 digits): 4.7529155256159980531876290929438093413108253981451
Boost Multiprecision  (99 digits): 4.75291552561599805318762909294380934131082539814514244132288567973008216166037385350291572422559648
Boost Multiprecision (100 digits): 4.752915525615998053187629092943809341310825398145142441322885679730082161660373853502915724225596483
Boost Multiprecision (101 digits): 4.7529155256159980531876290929438093413108253981451424413228856797300821616603738535029157242255964827
Boost Multiprecision  (Quadruple): 4.75291552561599805318762909294381
-------------------------------------------
*/