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