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/*! \internal \file
 *
 * \brief
 * Declares the DimParams struct and AWH vector types.
 *
 * This class holds the physical information for a dimension
 * of the bias reaction-coordinate grid.
 *
 * \author Viveca Lindahl
 * \author Berk Hess <hess@kth.se>
 * \ingroup module_awh
 */

#ifndef GMX_AWH_DIMPARAMS_H
#define GMX_AWH_DIMPARAMS_H

#include <vector>

#include "gromacs/math/vectypes.h"
#include "gromacs/utility/basedefinitions.h"

namespace gmx
{

//! The maximum dimensionality of the AWH coordinate.
static const int c_biasMaxNumDim = 4;

//! A real vector in AWH coordinate space.
typedef double awh_dvec[c_biasMaxNumDim];

//! An integer vector in AWH coordinate space.
typedef int awh_ivec[c_biasMaxNumDim];

/*! \internal \brief Constant parameters for each dimension of the coordinate.
 */
struct DimParams
{
    /*! \brief
     * Constructor.
     *
     * \param[in] conversionFactor  Conversion factor from user coordinate units to bias internal units (=DEG2RAD for angles).
     * \param[in] forceConstant     The harmonic force constant.
     * \param[in] beta              1/(k_B T).
     */
    DimParams(double conversionFactor, double forceConstant, double beta) :
        k(forceConstant),
        betak(beta * forceConstant),
        userCoordUnitsToInternal(conversionFactor)
    {
    }

    /*! \brief Convert internal coordinate units to external, user coordinate units.
     *
     * \param[in] value               Value to convert.
     * \returns the converted value.
     */
    double scaleInternalToUserInput(double value) const { return value / userCoordUnitsToInternal; }

    /*! \brief Convert external, user coordinate units to internal coordinate units.
     *
     * \param[in] value               Value to convert.
     * \returns the converted value.
     */
    double scaleUserInputToInternal(double value) const { return value * userCoordUnitsToInternal; }

    const double k;     /**< Force constant (kJ/mol/nm^2) for each coordinate dimension. */
    const double betak; /**< Inverse variance (1/nm^2) for each coordinate dimension. */
    const double userCoordUnitsToInternal; /**< Conversion factor coordinate units. */
};

} // namespace gmx

#endif /* GMX_AWH_DIMPARAMS_H */
