JointMarginal.h

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/* ----------------------------------------------------------------------------
 
 * GTSAM Copyright 2010, Georgia Tech Research Corporation,
 * Atlanta, Georgia 30332-0415
 * All Rights Reserved
 * Authors: Frank Dellaert, et al. (see THANKS for the full author list)
 
 * See LICENSE for the license information
 
 * -------------------------------------------------------------------------- */

 
#pragma once
 
#include <gtsam/linear/Scatter.h>
#include <gtsam/inference/Key.h>
#include <gtsam/base/SymmetricBlockMatrix.h>
 
namespace gtsam {
 
class GaussianBayesTree;
class ISAM2;
class Marginals;

class GTSAM_EXPORT JointMarginal {
 protected:
  SymmetricBlockMatrix blockMatrix_;
  KeyVector keys_;
  FastMap<Key, size_t> indices_;
 
 public:
  JointMarginal() {}

  Matrix operator()(Key iVariable, Key jVariable) const {
    const auto indexI = indices_.at(iVariable);
    const auto indexJ = indices_.at(jVariable);
    return blockMatrix_.block(indexI, indexJ);
  }

  Matrix at(Key iVariable, Key jVariable) const { return (*this)(iVariable, jVariable); }

  Matrix fullMatrix() const { return blockMatrix_.selfadjointView(); }

  void print(const std::string& s = "",
             const KeyFormatter& formatter = DefaultKeyFormatter) const;

  JointMarginal(const Matrix& fullMatrix, const Scatter& scatter);
};
 
}  // namespace gtsam