// test_circle_area.cpp

// (C) Copyright Paul A Bristow, hetp Chromatography, 2003
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" with express or implied warranty,
// and with no claim as to its suitability for any purpose.

#include <iostream>
#include <limits> // for numeric_limits

#include "function_constants.hpp"

using std::cout;
using std::endl;

const char nl = '\n';
const char tab = '\t';
const char space = ' ';

// Question posed by Joerg Walter, 22 Jan 2003 22:14

template <typename T>
T circle_area(const T& radius)
{
  // Usage example:   circle_area<double>( 2.)
  // or   circle_area(2.F)
	return boost::math::constant< T, boost::math::pi_tag >() * radius * radius;
}

int main()
{
	cout << "Test " << __FILE__ << ' ' << __TIMESTAMP__ << endl;
	
	// Calculate number of significant digits, strictly
	// ceil(1 + std::numeric_limits<float>::digits*log10(2.))
	// but need an approximation that does not use floating-point
	// to compute correctly at compile time.
	int float_significand_digits =  std::numeric_limits<float>::digits; // 24 bits
	int float_significant_digits =  2 + float_significand_digits * 30101/100000;
	int double_significand_digits =  std::numeric_limits<double>::digits; // 53 bits
	int double_significant_digits =  2 + double_significand_digits * 30101/100000; // 53 bits for MSVC
	cout.precision(double_significant_digits);// Ensure they are all output.

	// This is needed to show the difference between pi float and double
	// (and long double if not MSVC).

	// Or for using float and double constants at the same time,
	// users can explicitly access fully specified constants at any time:
	cout.precision(float_significant_digits);
	// Ensure all float significant (9) digits are displayed.
	cout << "float pi = " << boost::math::float_constants::pi << "\n"; //  3.14159274
	cout.precision(double_significant_digits);
	cout << "double pi = " << boost::math::double_constants::pi << "\n"; // 3.1415926535897931
	cout << "float pi = " << boost::math::float_constants::pi << "\n"; // double_sig_digits 3.1415927410125732

	cout << "circle_area<float>(1.) = "  << circle_area<float>(1.) << endl; // Explicit type float.
	cout << "circle_area<double>(1.) = "  << circle_area<double>(1.) << endl; // Explicit type 
	cout << "circle_area(1.F) = "  << circle_area(1.F) << endl; // Implicit type float.
	cout << "circle_area(1.) = "  << circle_area(1.) << endl; // Implicit type double.
	cout << "circle_area(1.L) = "  << circle_area(1.L) << endl; // implicit type long double.
	cout << "circle_area<double>(1.F) = "  << circle_area<double>(1.F) << endl; // Explicit over-rides implicit.
	cout << "circle_area<long double>(1.) = "  << circle_area<long double>(1.)<< endl; // same as double for MSVC.
  // cout << "circle_area(1) = "  << circle_area(1)<< endl; // Implicit int - does not link!
  // cout << "circle_area<int>(1.) = "  << circle_area<int>(1.)<< endl; // Explicit int - does not compile!

	cout << "circle_area<float>(2.) = "  << circle_area<float>(2.) << endl; // Explicit type float.
	cout << "circle_area<double>(2.) = "  << circle_area<double>(2.) << endl; // Explicit type 
	cout << "circle_area(2.F) = "  << circle_area(2.F) << endl; // Implicit type float.
	cout << "circle_area(2.) = "  << circle_area(2.) << endl; // Implicit type double.
	cout << "circle_area(2.L) = "  << circle_area(2.L) << endl; // implicit type long double.
	cout << "circle_area<double>(2.F) = "  << circle_area<double>(2.F) << endl; // Explicit over-rides implicit.

	float pi_f = boost::math::constant< float, boost::math::pi_tag >();
	cout << "boost::math::constant< float, boost::math::pi_tag >() " << pi_f << endl;

	return 0;
} // int main()



/*

Output is

Test test_circle_area.cpp Thu Jan 23 00:06:28 2003
float pi = 3.14159274
double pi = 3.1415926535897931
float pi = 3.1415927410125732
circle_area<float>(1.) = 3.1415927410125732
circle_area<double>(1.) = 3.1415926535897931
circle_area(1.F) = 3.1415927410125732
circle_area(1.) = 3.1415926535897931
circle_area(1.L) = 3.1415926535897931
circle_area<double>(1.F) = 3.1415926535897931
circle_area<long double>(1.) = 3.1415926535897931
circle_area<float>(2.) = 12.566370964050293
circle_area<double>(2.) = 12.566370614359172
circle_area(2.F) = 12.566370964050293
circle_area(2.) = 12.566370614359172
circle_area(2.L) = 12.566370614359172
circle_area<double>(2.F) = 12.566370614359172
boost::math::constant< float, boost::math::pi_tag >() 3.1415927410125732
Press any key to continue


*/