70 lines
2.1 KiB
C
70 lines
2.1 KiB
C
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// This file is part of libigl, a simple c++ geometry processing library.
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//
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// Copyright (C) 2017 Daniele Panozzo <daniele.panozzo@gmail.com>
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//
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// This Source Code Form is subject to the terms of the Mozilla Public License
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// v. 2.0. If a copy of the MPL was not distributed with this file, You can
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// obtain one at http://mozilla.org/MPL/2.0/.
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#ifndef IGL_SLICE_CACHED_H
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#define IGL_SLICE_CACHED_H
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#include "igl_inline.h"
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#define EIGEN_YES_I_KNOW_SPARSE_MODULE_IS_NOT_STABLE_YET
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#include <Eigen/Dense>
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#include <Eigen/Sparse>
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namespace igl
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{
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// Act like the matlab X(row_indices,col_indices) operator, where row_indices,
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// col_indices are non-negative integer indices. This is a fast version of
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// igl::slice that can analyze and store the sparsity structure. It is slower
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// at the irst evaluation (slice_cached_precompute), but faster on the
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// subsequent ones.
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//
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// Inputs:
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// X m by n matrix
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// R list of row indices
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// C list of column indices
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//
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// Output:
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// Y #R by #C matrix
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// data Temporary data used by slice_cached to repeat this operation
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//
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// Usage:
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//
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// // Construct and slice up Laplacian
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// SparseMatrix<double> L,L_sliced;
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// igl::cotmatrix(V,F,L);
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// // Normal igl::slice call
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// igl::slice(L,in,in,L_in_in);
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// // Fast version
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// static VectorXi data; // static or saved in a global state
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// if (data.size() == 0)
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// igl::slice_cached_precompute(L,in,in,data,L_sliced);
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// else
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// igl::slice_cached(L,data,L_sliced);
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template <typename TX, typename TY, typename DerivedI>
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IGL_INLINE void slice_cached_precompute(
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const Eigen::SparseMatrix<TX>& X,
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const Eigen::Matrix<int,Eigen::Dynamic,1> & R,
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const Eigen::Matrix<int,Eigen::Dynamic,1> & C,
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Eigen::MatrixBase<DerivedI>& data,
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Eigen::SparseMatrix<TY>& Y
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);
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template <typename TX, typename TY, typename DerivedI>
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IGL_INLINE void slice_cached(
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const Eigen::SparseMatrix<TX>& X,
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const Eigen::MatrixBase<DerivedI>& data,
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Eigen::SparseMatrix<TY>& Y
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);
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}
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#ifndef IGL_STATIC_LIBRARY
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# include "slice_cached.cpp"
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#endif
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#endif
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