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Combinatorics.h
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//# Smooth.h: smooth vectors and arrays
//# Copyright (C) 2010 by ESO (in the framework of the ALMA collaboration)
//# Copyright (C) 1996,1997,1998,1999,2000,2001
//# Associated Universities, Inc. Washington DC, USA.
//#
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//#
//# This library is distributed in the hope that it will be useful, but WITHOUT
//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
//# License for more details.
//#
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//#
//# Correspondence concerning AIPS++ should be addressed as follows:
//# Internet email: casa-feedback@nrao.edu.
//# Postal address: AIPS++ Project Office
//# National Radio Astronomy Observatory
//# 520 Edgemont Road
//# Charlottesville, VA 22903-2475 USA
#ifndef SCIMATH_COMBINATORICS_H
#define SCIMATH_COMBINATORICS_H
//# Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/Arrays/Vector.h>
#include <mutex>
namespace casacore { //# NAMESPACE CASACORE - BEGIN
// <summary>
// Combinatorics related functions.
// </summary>
// <use visibility=export>
//# <author>Dave Mehringer</author>
// <reviewed reviewer="" date="yyyy/mm/dd" tests="" demos="">
// </reviewed>
// <prerequisite>
// <li> <linkto class="Vector">Vector</linkto>
// <li> <linkto class="Array">Array</linkto>
// </prerequisite>
// <etymology>
// self-explanatory
// </etymology>
// <synopsis>
// Various factorial and combinatorical functions.
// </synopsis>
// <motivation>
// Binomial coefficients needed for Images/ImageProfileFitter
// </motivation>
class Combinatorics {
public:
// Get n!
static uInt factorial(const uInt n)
{
fillCache(n);
return _factorialCache[n];
}
// "n choose k" = n!/(k!(n-k)!)
// Exception is thrown if k > n.
static uInt choose(const uInt n, const uInt k);
private:
static void fillCache(const uInt n);
static Vector<uInt> _factorialCache;
static volatile uInt _factorialCacheSize; //# volatile for double checked lock
static std::mutex theirMutex;
};
} //# NAMESPACE CASACORE - END
#endif
casacore::Combinatorics
Definition Combinatorics.h:66
casacore::Combinatorics::factorial
static uInt factorial(const uInt n)
Get n!
Definition Combinatorics.h:71
casacore::Combinatorics::choose
static uInt choose(const uInt n, const uInt k)
"n choose k" = n!
casacore::Combinatorics::_factorialCache
static Vector< uInt > _factorialCache
Definition Combinatorics.h:84
casacore::Combinatorics::fillCache
static void fillCache(const uInt n)
casacore::Combinatorics::_factorialCacheSize
static volatile uInt _factorialCacheSize
Definition Combinatorics.h:85
casacore::Combinatorics::theirMutex
static std::mutex theirMutex
Definition Combinatorics.h:86
casacore::Vector
Definition Vector.h:82
casacore
this file contains all the compiler specific defines
Definition mainpage.dox:28
casacore::uInt
unsigned int uInt
Definition aipstype.h:49