casacore
Combinatorics.h
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1 //# Smooth.h: smooth vectors and arrays
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27 //# $Id$
28 
29 #ifndef SCIMATH_COMBINATORICS_H
30 #define SCIMATH_COMBINATORICS_H
31 
32 
33 //# Includes
34 #include <casacore/casa/aips.h>
35 #include <casacore/casa/Arrays/Vector.h>
36 
37 #include <mutex>
38 
39 namespace casacore { //# NAMESPACE CASACORE - BEGIN
40 
41 // <summary>
42 // Combinatorics related functions.
43 // </summary>
44 
45 // <use visibility=export>
46 
47 //# <author>Dave Mehringer</author>
48 // <reviewed reviewer="" date="yyyy/mm/dd" tests="" demos="">
49 // </reviewed>
50 
51 // <prerequisite>
52 // <li> <linkto class="Vector">Vector</linkto>
53 // <li> <linkto class="Array">Array</linkto>
54 // </prerequisite>
55 
56 // <etymology>
57 // self-explanatory
58 // </etymology>
59 
60 // <synopsis>
61 // Various factorial and combinatorical functions.
62 // </synopsis>
63 
64 // <motivation>
65 // Binomial coefficients needed for Images/ImageProfileFitter
66 // </motivation>
67 
69 
70  public:
71 
72  // Get n!
73  static uInt factorial(const uInt n)
74  {
75  fillCache(n);
76  return _factorialCache[n];
77  }
78 
79  // "n choose k" = n!/(k!(n-k)!)
80  // Exception is thrown if k > n.
81  static uInt choose(const uInt n, const uInt k);
82 
83  private:
84  static void fillCache(const uInt n);
85 
87  static volatile uInt _factorialCacheSize; //# volatile for double checked lock
88  static std::mutex theirMutex;
89 };
90 } //# NAMESPACE CASACORE - END
91 
92 #endif
93 
static uInt factorial(const uInt n)
Get n!
Definition: Combinatorics.h:73
static uInt choose(const uInt n, const uInt k)
"n choose k" = n!/(k!(n-k)!) Exception is thrown if k > n.
static Vector< uInt > _factorialCache
Definition: Combinatorics.h:86
static void fillCache(const uInt n)
static volatile uInt _factorialCacheSize
Definition: Combinatorics.h:87
static std::mutex theirMutex
Definition: Combinatorics.h:88
this file contains all the compiler specific defines
Definition: mainpage.dox:28
unsigned int uInt
Definition: aipstype.h:51