ABACUS/include/ABACUS_Combi.h

/**********************************************************

This software is part of J.-S. Caux's ABACUS library.

Copyright (c) J.-S. Caux.

-----------------------------------------------------------

File:  ABACUS_Combi.h

Purpose:  Declares combinatorics-related classes and functions.

***********************************************************/

#ifndef ABACUS_COMBI_H
#define ABACUS_COMBI_H

#include "ABACUS.h"

namespace ABACUS {

  //***********************************************************************

  class Choose_Table {

  private:
    int Npower;
    int Npowerp1;
    int dim;
    unsigned long long int* table;
    void Fill_table ();

  public:
    Choose_Table ();
    Choose_Table (int Npower_ref);
    Choose_Table (const Choose_Table& Ref_Choose_Table); // constructs a new object from an existing one
    int power();  // returns Npower
    unsigned long long int choose (int N, int M);
    ~Choose_Table ();

  };


  std::ostream& operator<< (std::ostream& s, Choose_Table& Ref_table);


} // namespace ABACUS

#endif