1 // TestFactorial.cpp
2 //
3 // Factorials and Binomial Coefficients.
4 //
5 // Copyright Datasim Education BV 2009-2010
6 // Copyright John Maddock and Paul A. Bristow 2010
7
8 // Use, modification and distribution are subject to the
9 // Boost Software License, Version 1.0.
10 // (See accompanying file LICENSE_1_0.txt
11 // or copy at http://www.boost.org/LICENSE_1_0.txt)
12
13 #include <boost/math/special_functions/factorials.hpp>
14 #include <boost/math/special_functions.hpp>
15
16 #include <iostream>
17 using namespace std;
18
main()19 int main()
20 {
21 using namespace boost::math;
22
23 // Factorials
24 unsigned int n = 3;
25
26 try
27 {
28 cout << "Factorial: " << factorial<double>(n) << endl;
29
30 // Caution: You must provide a return type template value, so this will not compile
31 // unsigned int nfac = factorial(n); // could not deduce template argument for 'T'
32 // You must provide an explicit floating-point (not integer) return type.
33 // If you do provide an integer type, like this:
34 // unsigned int uintfac = factorial<unsigned int>(n);
35 // you will also get a compile error, for MSVC C2338.
36 // If you really want an integer type, you can convert from double:
37 unsigned int intfac = static_cast<unsigned int>(factorial<double>(n));
38 // this will be exact, until the result of the factorial overflows the integer type.
39
40 cout << "Unchecked factorial: " << boost::math::unchecked_factorial<float>(n) << endl;
41 // Note:
42 // unsigned int unfac = boost::math::unchecked_factorial<unsigned int>(n);
43 // also fails to compile for the same reasons.
44 }
45 catch(exception& e)
46 {
47 cout << e.what() << endl;
48 }
49
50 // Double factorial n!!
51 try
52 {
53 //cout << "Double factorial: " << boost::math::double_factorial<unsigned>(n);
54 }
55 catch(exception& e)
56 {
57 cout << e.what() << endl;
58 }
59
60 // Rising and falling factorials
61 try
62 {
63 int i = 2; double x = 8;
64 cout << "Rising factorial: " << rising_factorial(x,i) << endl;
65 cout << "Falling factorial: " << falling_factorial(x,i) << endl;
66 }
67 catch(exception& e)
68 {
69 cout << e.what() << endl;
70 }
71
72 // Binomial coefficients
73 try
74 {
75 unsigned n = 10; unsigned k = 2;
76 // cout << "Binomial coefficient: " << boost::math::binomial_coefficient<unsigned>(n,k) << endl;
77 }
78 catch(exception& e)
79 {
80 cout << e.what() << endl;
81 }
82 return 0;
83 }
84
85 /*
86
87 Output:
88
89 factorial_example.vcxproj -> J:\Cpp\MathToolkit\test\Math_test\Release\factorial_example.exe
90 Factorial: 6
91 Unchecked factorial: 6
92 Rising factorial: 72
93 Falling factorial: 56
94
95 */
96
97
98