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

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

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// Author: richie.stebbing@gmail.com (Richard Stebbing)

//

// A jacobian writer that directly writes to dynamic compressed row sparse

// matrices.

#ifndef CERES_INTERNAL_DYNAMIC_COMPRESSED_ROW_JACOBIAN_WRITER_H_

#define CERES_INTERNAL_DYNAMIC_COMPRESSED_ROW_JACOBIAN_WRITER_H_

#include "ceres/evaluator.h"

#include "ceres/scratch_evaluate_preparer.h"

namespace ceres {

namespace internal {

class Program;

class SparseMatrix;

class DynamicCompressedRowJacobianWriter {

 public:

  DynamicCompressedRowJacobianWriter(Evaluator::Options /* ignored */,

                                     Program* program)

    : program_(program) {

  }

  // JacobianWriter interface.

  // The compressed row matrix has different layout than that assumed by

  // the cost functions. The scratch space is therefore used to store

  // the jacobians (including zeros) temporarily before only the non-zero

  // entries are copied over to the larger jacobian in `Write`.

  ScratchEvaluatePreparer* CreateEvaluatePreparers(int num_threads);

  // Return a `DynamicCompressedRowSparseMatrix` which is filled by

  // `Write`. Note that `Finalize` must be called to make the

  // `CompressedRowSparseMatrix` interface valid.

  SparseMatrix* CreateJacobian() const;

  // Write only the non-zero jacobian entries for a residual block

  // (specified by `residual_id`) into `base_jacobian`, starting at the row

  // specifed by `residual_offset`.

  //

  // This method is thread-safe over residual blocks (each `residual_id`).

  void Write(int residual_id,

             int residual_offset,

             double **jacobians,

             SparseMatrix* base_jacobian);

 private:

  Program* program_;

};

}  // namespace internal

}  // namespace ceres

#endif  // CERES_INTERNAL_DYNAMIC_COMPRESSED_ROW_JACOBIAN_WRITER_H_