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// 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/.
#ifndef IGL_FIND_H
#define IGL_FIND_H
#include "igl_inline.h"
#define EIGEN_YES_I_KNOW_SPARSE_MODULE_IS_NOT_STABLE_YET
#include <Eigen/Dense>
#include <Eigen/Sparse>
#include <vector>
namespace igl
{
/// Find the non-zero entries and there respective indices in a sparse matrix.
/// Like matlab's [I,J,V] = find(X)
///
/// @tparam T should be a eigen sparse matrix primitive type like int or double
/// @param[in] X m by n matrix whose entries are to be found
/// @param[out] I nnz vector of row indices of non zeros entries in X
/// @param[out] J nnz vector of column indices of non zeros entries in X
/// @param[out] V nnz vector of type T non-zeros entries in X
///
template <
typename T,
typename DerivedI,
typename DerivedJ,
typename DerivedV>
IGL_INLINE void find(
const Eigen::SparseMatrix<T>& X,
Eigen::DenseBase<DerivedI> & I,
Eigen::DenseBase<DerivedJ> & J,
Eigen::DenseBase<DerivedV> & V);
/// \overload
template < typename T>
IGL_INLINE std::vector<Eigen::Triplet<T> > find(
const Eigen::SparseMatrix<T>& X);
/// \overload
template <
typename DerivedX,
typename DerivedI,
typename DerivedJ,
typename DerivedV>
IGL_INLINE void find(
const Eigen::DenseBase<DerivedX>& X,
Eigen::PlainObjectBase<DerivedI> & I,
Eigen::PlainObjectBase<DerivedJ> & J,
Eigen::PlainObjectBase<DerivedV> & V);
/// \overload
///
/// @param[out] I nnz vector of indices into vectorization of X
template <
typename DerivedX,
typename DerivedI>
IGL_INLINE void find(
const Eigen::DenseBase<DerivedX>& X,
Eigen::PlainObjectBase<DerivedI> & I);
/// \overload
template <typename T>
IGL_INLINE void find(
const Eigen::SparseVector<T>& X,
Eigen::Matrix<int,Eigen::Dynamic,1> & I,
Eigen::Matrix<T,Eigen::Dynamic,1> & V);
/// \overload
/// \brief This overload facilitates the use of bool masks for Eigen slicing
/// @tparam RowsAtCompileTime number of rows in M at compile time
/// @return indices of true entries in M
///
/// ##### Example
///
/// ```cpp
/// igl::slice_mask(A,igl::find(M),igl::find(N),B);
/// // Is the same as
/// B = A(igl::find(M),igl::find(N));
/// ```
///
/// \see slice_mask
template <int RowsAtCompileTime, int MaxRowsAtCompileTime>
IGL_INLINE std::vector<int> find(
const Eigen::Array<bool,RowsAtCompileTime,1,0,MaxRowsAtCompileTime,1> & M);
}
#ifndef IGL_STATIC_LIBRARY
# include "find.cpp"
#endif
#endif