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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:
//
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// 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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//
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//
// Author: sameeragarwal@google.com (Sameer Agarwal)
//
// Interface definition for sparse matrices.
#ifndef CERES_INTERNAL_SPARSE_MATRIX_H_
#define CERES_INTERNAL_SPARSE_MATRIX_H_
#include <cstdio>
#include "ceres/internal/eigen.h"
#include "ceres/internal/export.h"
#include "ceres/linear_operator.h"
#include "ceres/types.h"
namespace ceres::internal {
// This class defines the interface for storing and manipulating
// sparse matrices. The key property that differentiates different
// sparse matrices is how they are organized in memory and how the
// information about the sparsity structure of the matrix is
// stored. This has significant implications for linear solvers
// operating on these matrices.
//
// To deal with the different kinds of layouts, we will assume that a
// sparse matrix will have a two part representation. A values array
// that will be used to store the entries of the sparse matrix and
// some sort of a layout object that tells the user the sparsity
// structure and layout of the values array. For example in case of
// the TripletSparseMatrix, this information is carried in the rows
// and cols arrays and for the BlockSparseMatrix, this information is
// carried in the CompressedRowBlockStructure object.
//
// This interface deliberately does not contain any information about
// the structure of the sparse matrix as that seems to be highly
// matrix type dependent and we are at this stage unable to come up
// with an efficient high level interface that spans multiple sparse
// matrix types.
class CERES_NO_EXPORT SparseMatrix : public LinearOperator {
public:
~SparseMatrix() override;
// y += Ax;
void RightMultiplyAndAccumulate(const double* x,
double* y) const override = 0;
// y += A'x;
void LeftMultiplyAndAccumulate(const double* x, double* y) const override = 0;
// In MATLAB notation sum(A.*A, 1)
virtual void SquaredColumnNorm(double* x) const = 0;
// A = A * diag(scale)
virtual void ScaleColumns(const double* scale) = 0;
// A = 0. A->num_nonzeros() == 0 is true after this call. The
// sparsity pattern is preserved.
virtual void SetZero() = 0;
// Resize and populate dense_matrix with a dense version of the
// sparse matrix.
virtual void ToDenseMatrix(Matrix* dense_matrix) const = 0;
// Write out the matrix as a sequence of (i,j,s) triplets. This
// format is useful for loading the matrix into MATLAB/octave as a
// sparse matrix.
virtual void ToTextFile(FILE* file) const = 0;
// Accessors for the values array that stores the entries of the
// sparse matrix. The exact interpretation of the values of this
// array depends on the particular kind of SparseMatrix being
// accessed.
virtual double* mutable_values() = 0;
virtual const double* values() const = 0;
int num_rows() const override = 0;
int num_cols() const override = 0;
virtual int num_nonzeros() const = 0;
};
} // namespace ceres::internal
#endif // CERES_INTERNAL_SPARSE_MATRIX_H_