libigl_Martin/include/igl/cumsum.cpp

// This file is part of libigl, a simple c++ geometry processing library.
// 
// Copyright (C) 2013 Alec Jacobson <alecjacobson@gmail.com>
// 
// 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/.
#include "cumsum.h"
#include <numeric>
#include <iostream>

template <typename DerivedX, typename DerivedY>
IGL_INLINE void igl::cumsum(
  const Eigen::PlainObjectBase<DerivedX > & X,
  const int dim,
  Eigen::PlainObjectBase<DerivedY > & Y)
{
  using namespace Eigen;
  using namespace std;
  Y.resize(X.rows(),X.cols());
  // get number of columns (or rows)
  int num_outer = (dim == 1 ? X.cols() : X.rows() );
  // get number of rows (or columns)
  int num_inner = (dim == 1 ? X.rows() : X.cols() );
  // This has been optimized so that dim = 1 or 2 is roughly the same cost.
  // (Optimizations assume ColMajor order)
  if(dim == 1)
  {
#pragma omp parallel for
    for(int o = 0;o<num_outer;o++)
    {
      typename DerivedX::Scalar sum = 0;
      for(int i = 0;i<num_inner;i++)
      {
        sum += X(i,o);
        Y(i,o) = sum;
      }
    }
  }else
  {
    for(int i = 0;i<num_inner;i++)
    {
      // Notice that it is *not* OK to put this above the inner loop
      // Though here it doesn't seem to pay off...
//#pragma omp parallel for
      for(int o = 0;o<num_outer;o++)
      {
        if(i == 0)
        {
          Y(o,i) = X(o,i);
        }else
        {
          Y(o,i) = Y(o,i-1) + X(o,i);
        }
      }
    }
  }
}

#ifdef IGL_STATIC_LIBRARY
// Explicit template specialization
template void igl::cumsum<Eigen::Matrix<double, -1, -1, 0, -1, -1>, Eigen::Matrix<double, -1, -1, 0, -1, -1> >(Eigen::PlainObjectBase<Eigen::Matrix<double, -1, -1, 0, -1, -1> > const&, int, Eigen::PlainObjectBase<Eigen::Matrix<double, -1, -1, 0, -1, -1> >&);
template void igl::cumsum<Eigen::Matrix<double, -1, 1, 0, -1, 1>, Eigen::Matrix<double, -1, 1, 0, -1, 1> >(Eigen::PlainObjectBase<Eigen::Matrix<double, -1, 1, 0, -1, 1> > const&, int, Eigen::PlainObjectBase<Eigen::Matrix<double, -1, 1, 0, -1, 1> >&);
template void igl::cumsum<Eigen::Matrix<double, 3, 1, 0, 3, 1>, Eigen::Matrix<double, 3, 1, 0, 3, 1> >(Eigen::PlainObjectBase<Eigen::Matrix<double, 3, 1, 0, 3, 1> > const&, int, Eigen::PlainObjectBase<Eigen::Matrix<double, 3, 1, 0, 3, 1> >&);
template void igl::cumsum<Eigen::Matrix<unsigned long, 2, 1, 0, 2, 1>, Eigen::Matrix<unsigned long, 2, 1, 0, 2, 1> >(Eigen::PlainObjectBase<Eigen::Matrix<unsigned long, 2, 1, 0, 2, 1> > const&, int, Eigen::PlainObjectBase<Eigen::Matrix<unsigned long, 2, 1, 0, 2, 1> >&);
template void igl::cumsum<Eigen::Matrix<unsigned long, -1, 1, 0, -1, 1>, Eigen::Matrix<unsigned long, -1, 1, 0, -1, 1> >(Eigen::PlainObjectBase<Eigen::Matrix<unsigned long, -1, 1, 0, -1, 1> > const&, int, Eigen::PlainObjectBase<Eigen::Matrix<unsigned long, -1, 1, 0, -1, 1> >&);
#endif