libigl/include/igl/sum.h

// This file is part of libigl, a simple c++ geometry processing library.
// 
// Copyright (C) 2013 Alec Jacobson <[email protected]>
// 
// 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_SUM_H
#define IGL_SUM_H
#include "igl_inline.h"
#include <Eigen/Sparse>

namespace igl
{
  /// Sum the columns or rows of a sparse matrix
  ///
  /// @tparam  should be a eigen sparse matrix primitive type like int or double
  /// @param[in] X  m by n sparse matrix
  /// @param[in] dim  dimension along which to sum (1 or 2)
  /// @param[out] S  n-long sparse vector (if dim == 1) 
  ///   or m-long sparse vector (if dim == 2)
  ///
  /// \note If your looking for dense matrix matlab like sum for eigen matrics
  /// just use:
  ///
  ///      M.colwise().sum() or M.rowwise().sum()
  /// 
  template <typename T>
  IGL_INLINE void sum(
    const Eigen::SparseMatrix<T>& X, 
    const int dim,
    Eigen::SparseVector<T>& S);
  /// \overload
  /// \brief Sum is "conducted" in the type of DerivedB::Scalar 
  /// @tparam AType  should be a eigen sparse matrix primitive type like int or double
  /// @tparam DerivedB  should be a eigen dense matrix primitive type like int or double
  template <typename AType, typename DerivedB>
  IGL_INLINE void sum(
    const Eigen::SparseMatrix<AType> & A, 
    const int dim,
    Eigen::PlainObjectBase<DerivedB>& B);
}

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

#endif