RotationConstraint.h

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// Copyright (C) 2020 ASTRON (Netherlands Institute for Radio Astronomy)
// SPDX-License-Identifier: GPL-3.0-or-later
 
#ifndef DP3_DDECAL_ROTATION_CONSTRAINT_H_
#define DP3_DDECAL_ROTATION_CONSTRAINT_H_
 
#include "Constraint.h"
 
#include <vector>
#include <ostream>
 
namespace dp3::ddecal {
 
class RotationConstraint final : public Constraint {
 public:
  RotationConstraint() = default;
 
  void Apply(SolutionSpan& solutions, double time) override;
 
  void Initialize(size_t n_antennas,
                  const std::vector<uint32_t>& solutions_per_direction,
                  const std::vector<double>& frequencies) override;
 
  void SetWeights(const std::vector<double>& weights) override;
 
  std::vector<ConstraintResult> GetResult() const override { return results_; }
 
  /* Compute the rotation from a 2x2 full jones solution */
  static double FitRotation(const std::complex<double>* data) {
    // Convert to circular
    const dcomplex i(0, 1.);
 
    const dcomplex ll = data[0] + data[3] + i * (data[2] - data[1]);
    const dcomplex rr = data[0] + data[3] + i * (data[1] - data[2]);
    const double angle = 0.5 * (std::arg(ll) - std::arg(rr));
 
    return angle;
  }
 
  static void SetRotation(std::complex<double>* data, double angle) {
    data[0] = std::cos(angle);
    data[1] = -std::sin(angle);
    data[2] = -data[1];
    data[3] = data[0];
  }
 
 private:
  std::vector<ConstraintResult> results_;
};
 
}  // namespace dp3::ddecal
 
#endif