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// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2015 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of Google Inc. nor the names of its contributors may be
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// Author: keir@google.com (Keir Mierle)
#ifndef CERES_INTERNAL_BLOCK_JACOBI_PRECONDITIONER_H_
#define CERES_INTERNAL_BLOCK_JACOBI_PRECONDITIONER_H_
#include <memory>
#include "ceres/block_random_access_diagonal_matrix.h"
#include "ceres/preconditioner.h"
namespace ceres {
namespace internal {
class BlockSparseMatrix;
struct CompressedRowBlockStructure;
// A block Jacobi preconditioner. This is intended for use with
// conjugate gradients, or other iterative symmetric solvers. To use
// the preconditioner, create one by passing a BlockSparseMatrix "A"
// to the constructor. This fixes the sparsity pattern to the pattern
// of the matrix A^TA.
//
// Before each use of the preconditioner in a solve with conjugate gradients,
// update the matrix by running Update(A, D). The values of the matrix A are
// inspected to construct the preconditioner. The vector D is applied as the
// D^TD diagonal term.
class BlockJacobiPreconditioner : public BlockSparseMatrixPreconditioner {
public:
// A must remain valid while the BlockJacobiPreconditioner is.
explicit BlockJacobiPreconditioner(const BlockSparseMatrix& A);
BlockJacobiPreconditioner(const BlockJacobiPreconditioner&) = delete;
void operator=(const BlockJacobiPreconditioner&) = delete;
virtual ~BlockJacobiPreconditioner();
// Preconditioner interface
void RightMultiply(const double* x, double* y) const final;
int num_rows() const final { return m_->num_rows(); }
int num_cols() const final { return m_->num_rows(); }
const BlockRandomAccessDiagonalMatrix& matrix() const { return *m_; }
private:
bool UpdateImpl(const BlockSparseMatrix& A, const double* D) final;
std::unique_ptr<BlockRandomAccessDiagonalMatrix> m_;
};
} // namespace internal
} // namespace ceres
#endif // CERES_INTERNAL_BLOCK_JACOBI_PRECONDITIONER_H_