| // This file is part of libigl, a simple c++ geometry processing library. | |
| // | |
| // Copyright (C) 2017 Daniele Panozzo <daniele.panozzo@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/. | |
| namespace igl | |
| { | |
| struct AtA_cached_data | |
| { | |
| // Weights | |
| Eigen::VectorXd W; | |
| // Flatten composition rules | |
| std::vector<int> I_row; | |
| std::vector<int> I_col; | |
| std::vector<int> I_w; | |
| // For each entry of AtA, points to the beginning | |
| // of the composition rules | |
| std::vector<int> I_outer; | |
| }; | |
| // Computes At * W * A, where A is sparse and W is diagonal. Divides the | |
| // construction in two phases, one | |
| // for fixing the sparsity pattern, and one to populate it with values. Compared to | |
| // evaluating it directly, this version is slower for the first time (since it requires a | |
| // precomputation), but faster to the subsequent evaluations. | |
| // | |
| // Input: | |
| // A m x n sparse matrix | |
| // data stores the precomputed sparsity pattern, data.W contains the optional diagonal weights (stored as a dense vector). If W is not provided, it is replaced by the identity. | |
| // Outputs: | |
| // AtA m by m matrix computed as AtA * W * A | |
| // | |
| // Example: | |
| // AtA_data = igl::AtA_cached_data(); | |
| // AtA_data.W = W; | |
| // if (s.AtA.rows() == 0) | |
| // igl::AtA_cached_precompute(s.A,s.AtA_data,s.AtA); | |
| // else | |
| // igl::AtA_cached(s.A,s.AtA_data,s.AtA); | |
| template <typename Scalar> | |
| IGL_INLINE void AtA_cached_precompute( | |
| const Eigen::SparseMatrix<Scalar>& A, | |
| AtA_cached_data& data, | |
| Eigen::SparseMatrix<Scalar>& AtA | |
| ); | |
| template <typename Scalar> | |
| IGL_INLINE void AtA_cached( | |
| const Eigen::SparseMatrix<Scalar>& A, | |
| const AtA_cached_data& data, | |
| Eigen::SparseMatrix<Scalar>& AtA | |
| ); | |
| } | |