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// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2019 Jérémie Dumas <jeremie.dumas@ens-lyon.org>
//
// 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_SLICE_SORTED_H
#define IGL_SLICE_SORTED_H
#include "igl_inline.h"
#include <Eigen/Dense>
#include <Eigen/Sparse>
namespace igl
{
// Act like the matlab X(row_indices,col_indices) operator, where row_indices,
// col_indices are non-negative integer indices. This version is about 2x faster
// than igl::slice, but it assumes that the indices to slice with are already sorted.
//
// Inputs:
// X m by n matrix
// R list of row indices
// C list of column indices
//
// Output:
// Y #R by #C matrix
//
template <typename TX, typename TY, typename DerivedR, typename DerivedC>
IGL_INLINE void slice_sorted(const Eigen::SparseMatrix<TX> &X,
const Eigen::DenseBase<DerivedR> &R,
const Eigen::DenseBase<DerivedC> &C,
Eigen::SparseMatrix<TY> &Y);
} // namespace igl
#ifndef IGL_STATIC_LIBRARY
#include "slice_sorted.cpp"
#endif
#endif