libigl_Martin/include/igl/nchoosek.h

// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2015 Olga Diamanti, Alec Jacobson
//
// This Source Code Form is subject to the terms of the Mozilla Public License
// v. 2.0. If a copy of the MPL was not distributed with this file, You can
// obtain one at http://mozilla.org/MPL/2.0/.

#ifndef IGL_NCHOOSEK
#define IGL_NCHOOSEK
#include "igl_inline.h"
#include "deprecated.h"
#include <vector>

#include <Eigen/Core>

namespace igl 
{
  // NCHOOSEK  Like matlab's nchoosek.
  //
  // Inputs:
  //   n  total number elements
  //   k  size of sub-set to consider
  // Returns number of k-size combinations out of the set [1,...,n]
  IGL_INLINE double nchoosek(const int n, const int k);
  // 
  // Inputs:
  //   V  n-long vector of elements
  //   k  size of sub-set to consider
  // Outputs:
  //   U  nchoosek by k long matrix where each row is a unique k-size
  //     combination
  template < typename DerivedV, typename DerivedU>
  IGL_INLINE void nchoosek(
    const Eigen::PlainObjectBase<DerivedV> & V,
    const int k,
    Eigen::PlainObjectBase<DerivedU> & U);
  // This version has a strange interface and confusing parameters. It seems to
  // reproduce matlab's 
  //
  //     nchoosek(3:5,2) 
  //
  // Then one should use
  //
  //     igl::nchoosek(3,2,6,res);
  //
  IGL_INLINE 
  IGL_DEPRECATED(
  void nchoosek(
    int offset,
    int k,
    int N,
    std::vector<std::vector<int> > &allCombs));
}


#ifndef IGL_STATIC_LIBRARY
#include "nchoosek.cpp"
#endif


#endif /* defined(IGL_NCHOOSEK) */