// Ceres Solver - A fast non-linear least squares minimizer

// Copyright 2015 Google Inc. All rights reserved.

// http://ceres-solver.org/

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// Author: sameeragarwal@google.com (Sameer Agarwal)

#ifndef CERES_INTERNAL_REORDER_PROGRAM_H_

#define CERES_INTERNAL_REORDER_PROGRAM_H_

#include <string>

#include "ceres/internal/port.h"

#include "ceres/parameter_block_ordering.h"

#include "ceres/problem_impl.h"

#include "ceres/types.h"

namespace ceres {

namespace internal {

class Program;

// Reorder the parameter blocks in program using the ordering

bool ApplyOrdering(const ProblemImpl::ParameterMap& parameter_map,

                   const ParameterBlockOrdering& ordering,

                   Program* program,

                   std::string* error);

// Reorder the residuals for program, if necessary, so that the residuals

// involving each E block occur together. This is a necessary condition for the

// Schur eliminator, which works on these "row blocks" in the jacobian.

bool LexicographicallyOrderResidualBlocks(int size_of_first_elimination_group,

                                          Program* program,

                                          std::string* error);

// Schur type solvers require that all parameter blocks eliminated

// by the Schur eliminator occur before others and the residuals be

// sorted in lexicographic order of their parameter blocks.

//

// If the parameter_block_ordering only contains one elimination

// group then a maximal independent set is computed and used as the

// first elimination group, otherwise the user's ordering is used.

//

// If the linear solver type is SPARSE_SCHUR and support for

// constrained fill-reducing ordering is available in the sparse

// linear algebra library (SuiteSparse version >= 4.2.0) then

// columns of the schur complement matrix are ordered to reduce the

// fill-in the Cholesky factorization.

//

// Upon return, ordering contains the parameter block ordering that

// was used to order the program.

bool ReorderProgramForSchurTypeLinearSolver(

    LinearSolverType linear_solver_type,

    SparseLinearAlgebraLibraryType sparse_linear_algebra_library_type,

    const ProblemImpl::ParameterMap& parameter_map,

    ParameterBlockOrdering* parameter_block_ordering,

    Program* program,

    std::string* error);

// Sparse cholesky factorization routines when doing the sparse

// cholesky factorization of the Jacobian matrix, reorders its

// columns to reduce the fill-in. Compute this permutation and

// re-order the parameter blocks.

//

// When using SuiteSparse, if the parameter_block_ordering contains

// more than one elimination group and support for constrained

// fill-reducing ordering is available in the sparse linear algebra

// library (SuiteSparse version >= 4.2.0) then the fill reducing

// ordering will take it into account, otherwise it will be ignored.

bool ReorderProgramForSparseNormalCholesky(

    SparseLinearAlgebraLibraryType sparse_linear_algebra_library_type,

    const ParameterBlockOrdering& parameter_block_ordering,

    Program* program,

    std::string* error);

}  // namespace internal

}  // namespace ceres

#endif  // CERES_INTERNAL_REORDER_PROGRAM_