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// TestFactorial.cpp
//
// Factorials and Binomial Coefficients.
//
// Copyright Datasim Education BV 2009-2010
// Copyright John Maddock and Paul A. Bristow 2010
// Use, modification and distribution are subject to the
// Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt
// or copy at http://www.boost.org/LICENSE_1_0.txt)
#include <boost/math/special_functions/factorials.hpp>
#include <boost/math/special_functions.hpp>
#include <iostream>
using namespace std;
int main()
{
using namespace boost::math;
// Factorials
unsigned int n = 3;
try
{
cout << "Factorial: " << factorial<double>(n) << endl;
// Caution: You must provide a return type template value, so this will not compile
// unsigned int nfac = factorial(n); // could not deduce template argument for 'T'
// You must provide an explicit floating-point (not integer) return type.
// If you do provide an integer type, like this:
// unsigned int uintfac = factorial<unsigned int>(n);
// you will also get a compile error, for MSVC C2338.
// If you really want an integer type, you can convert from double:
unsigned int intfac = static_cast<unsigned int>(factorial<double>(n));
// this will be exact, until the result of the factorial overflows the integer type.
cout << "Unchecked factorial: " << boost::math::unchecked_factorial<float>(n) << endl;
// Note:
// unsigned int unfac = boost::math::unchecked_factorial<unsigned int>(n);
// also fails to compile for the same reasons.
}
catch(exception& e)
{
cout << e.what() << endl;
}
// Double factorial n!!
try
{
//cout << "Double factorial: " << boost::math::double_factorial<unsigned>(n);
}
catch(exception& e)
{
cout << e.what() << endl;
}
// Rising and falling factorials
try
{
int i = 2; double x = 8;
cout << "Rising factorial: " << rising_factorial(x,i) << endl;
cout << "Falling factorial: " << falling_factorial(x,i) << endl;
}
catch(exception& e)
{
cout << e.what() << endl;
}
// Binomial coefficients
try
{
unsigned n = 10; unsigned k = 2;
// cout << "Binomial coefficient: " << boost::math::binomial_coefficient<unsigned>(n,k) << endl;
}
catch(exception& e)
{
cout << e.what() << endl;
}
return 0;
}
/*
Output:
factorial_example.vcxproj -> J:\Cpp\MathToolkit\test\Math_test\Release\factorial_example.exe
Factorial: 6
Unchecked factorial: 6
Rising factorial: 72
Falling factorial: 56
*/
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