LogNormalMover.h

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/**
 *  \file IMP/core/LogNormalMover.h
 *  \brief A modifier that perturbs a point with a log-normal distribution.
 *
 *  Copyright 2007-2022 IMP Inventors. All rights reserved.
 *
 */

#ifndef IMPCORE_LOGNORMAL_MOVER_H
#define IMPCORE_LOGNORMAL_MOVER_H

#include <IMP/core/core_config.h>
#include "MonteCarloMover.h"

IMPCORE_BEGIN_NAMESPACE

//! Modify a set of continuous variables using a log-normal distribution.
/** \see MonteCarlo
    \see NormalMover
    \note While technically a log-normal distribution only applies to
    positively bounded variables, a log-normal perturbation has a 
    multiplicative effect that can be applied to negative variables
    as well.
 */
class IMPCOREEXPORT LogNormalMover : public MonteCarloMover {
  ParticleIndexes pis_;
  FloatKeys keys_;
  Float stddev_;
  algebra::VectorKDs originals_;

  void initialize(ParticleIndexes pis, FloatKeys keys, double radius);

  public:
    LogNormalMover(Model *m, ParticleIndex pi, const FloatKeys &vars,
                   double stddev);
    //! Move the x,y,z coordinates
    LogNormalMover(Model *m, ParticleIndex pi, double stddev);
#ifndef IMP_DOXYGEN
    /**  \param[in] sc The set of particles to perturb.
         \param[in] vars The variables to use (normally the keys for x,y,z)
         \param[in] sigma The standard deviation to use.
     */
    LogNormalMover(const ParticlesTemp &sc, const FloatKeys &vars,
                   Float sigma);

    LogNormalMover(const ParticlesTemp &sc, Float radius);
#endif

    void set_sigma(Float sigma) {
      IMP_USAGE_CHECK(sigma > 0, "Sigma must be positive");
      stddev_ = sigma;
    }

    Float get_sigma() const { return stddev_; }

  protected:
    virtual ModelObjectsTemp do_get_inputs() const override;
    virtual MonteCarloMoverResult do_propose() override;
    virtual void do_reject() override;
    IMP_OBJECT_METHODS(LogNormalMover);
};

IMPCORE_END_NAMESPACE

#endif /* IMPCORE_LOGNORMAL_MOVER_H */