core/HarmonicLowerBound.h

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/**
 *  \file IMP/core/HarmonicLowerBound.h    \brief Harmonic lower bound function.
 *
 *  Copyright 2007-2023 IMP Inventors. All rights reserved.
 */

#ifndef IMPCORE_HARMONIC_LOWER_BOUND_H
#define IMPCORE_HARMONIC_LOWER_BOUND_H

#include <IMP/core/core_config.h>
#include "Harmonic.h"
#include <cereal/access.hpp>
#include <cereal/types/base_class.hpp>

IMPCORE_BEGIN_NAMESPACE

//! Lower bound harmonic function (non-zero when feature < mean)
/** \see Harmonic
    \see HarmonicUpperBound
    \see TruncatedHarmonicLowerBound
*/
class HarmonicLowerBound : public Harmonic {
  friend class cereal::access;
  template<class Archive> void serialize(Archive &ar) {
    ar(cereal::base_class<Harmonic>(this));
  }
  IMP_OBJECT_SERIALIZE_DECL(HarmonicLowerBound);
 public:
  /** Create with the given mean and the spring constant k */
  HarmonicLowerBound(Float mean, Float k) : Harmonic(mean, k) {}
  HarmonicLowerBound() {}
  virtual double evaluate(double feature) const override {
    return feature >= Harmonic::get_mean() ? 0.0 : Harmonic::evaluate(feature);
  }
  virtual DerivativePair evaluate_with_derivative(double feature) const
      override {
    return feature >= Harmonic::get_mean()
               ? DerivativePair(0.0, 0.0)
               : Harmonic::evaluate_with_derivative(feature);
  }
  IMP_OBJECT_METHODS(HarmonicLowerBound);
};

IMPCORE_END_NAMESPACE

#endif /* IMPCORE_HARMONIC_LOWER_BOUND_H */