47 lines
1.4 KiB
C++
47 lines
1.4 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) 2013 Alec Jacobson <alecjacobson@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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#include "invert_diag.h"
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template <typename T>
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IGL_INLINE void igl::invert_diag(
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const Eigen::SparseMatrix<T>& X,
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Eigen::SparseMatrix<T>& Y)
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{
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#ifndef NDEBUG
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typename Eigen::SparseVector<T> dX = X.diagonal().sparseView();
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// Check that there are no zeros along the diagonal
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assert(dX.nonZeros() == dX.size());
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#endif
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// http://www.alecjacobson.com/weblog/?p=2552
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if(&Y != &X)
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{
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Y = X;
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}
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// Iterate over outside
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for(int k=0; k<Y.outerSize(); ++k)
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{
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// Iterate over inside
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for(typename Eigen::SparseMatrix<T>::InnerIterator it (Y,k); it; ++it)
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{
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if(it.col() == it.row())
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{
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T v = it.value();
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assert(v != 0);
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v = ((T)1.0)/v;
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Y.coeffRef(it.row(),it.col()) = v;
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}
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}
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}
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}
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#ifdef IGL_STATIC_LIBRARY
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// Explicit template instantiation
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template void igl::invert_diag<double>(Eigen::SparseMatrix<double, 0, int> const&, Eigen::SparseMatrix<double, 0, int>&);
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template void igl::invert_diag<float>(Eigen::SparseMatrix<float, 0, int> const&, Eigen::SparseMatrix<float, 0, int>&);
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#endif
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