score_functor/Harmonic.h

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/**
 *  \file IMP/score_functor/Harmonic.h
 *  \brief A Score on the distance between a pair of particles.
 *
 *  Copyright 2007-2014 IMP Inventors. All rights reserved.
 */

#ifndef IMPSCORE_FUNCTOR_HARMONIC_H
#define IMPSCORE_FUNCTOR_HARMONIC_H

#include <IMP/score_functor/score_functor_config.h>
#include "Score.h"
#include <IMP/algebra/utility.h>
IMPSCOREFUNCTOR_BEGIN_NAMESPACE

/** A DistanceScore that scores with a harmonic on the distance, centered
    at 0.*/
class Harmonic : public Score {
  double k_;

 public:
  Harmonic(double k) : k_(k) {}
  template <unsigned int D>
  double get_score(kernel::Model *,
                   const base::Array<D, kernel::ParticleIndex> &,
                   double distance) const {
    return .5 * k_ * algebra::get_squared(distance);
  }
  template <unsigned int D>
  DerivativePair get_score_and_derivative(
      kernel::Model *m, const base::Array<D, kernel::ParticleIndex> &p,
      double distance) const {
    return DerivativePair(get_score(m, p, distance), k_ * (distance));
  }
};

IMPSCOREFUNCTOR_END_NAMESPACE

#endif /* IMPSCORE_FUNCTOR_HARMONIC_H */