worldmagmodel.h

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/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, see <http://www.gnu.org/licenses/>
 */

#ifndef WORLDMAGMODEL_H
#define WORLDMAGMODEL_H

#include "utils_global.h"

// ******************************
// internal structure definitions

#define WMM_MAX_MODEL_DEGREES                       12
#define WMM_MAX_SECULAR_VARIATION_MODEL_DEGREES     12
#define WMM_NUMTERMS                                91          // ((WMM_MAX_MODEL_DEGREES + 1) * (WMM_MAX_MODEL_DEGREES + 2) / 2);
#define WMM_NUMPCUP                                 92          // NUMTERMS + 1
#define WMM_NUMPCUPS                                13          // WMM_MAX_MODEL_DEGREES + 1

typedef struct
{
    double EditionDate;
    double epoch;               //Base time of Geomagnetic model epoch (yrs)
    char ModelName[20];
//      double Main_Field_Coeff_G[WMM_NUMTERMS];        // C - Gauss coefficients of main geomagnetic model (nT)
//      double Main_Field_Coeff_H[WMM_NUMTERMS];        // C - Gauss coefficients of main geomagnetic model (nT)
//      double Secular_Var_Coeff_G[WMM_NUMTERMS];       // CD - Gauss coefficients of secular geomagnetic model (nT/yr)
//      double Secular_Var_Coeff_H[WMM_NUMTERMS];       // CD - Gauss coefficients of secular geomagnetic model (nT/yr)
    int nMax;           // Maximum degree of spherical harmonic model
    int nMaxSecVar;     // Maxumum degree of spherical harmonic secular model
    int SecularVariationUsed;   // Whether or not the magnetic secular variation vector will be needed by program
} WMMtype_MagneticModel;

typedef struct
{
    double a;           // semi-major axis of the ellipsoid
    double b;           // semi-minor axis of the ellipsoid
    double fla;         // flattening
    double epssq;       // first eccentricity squared
    double eps;         // first eccentricity
    double re;          // mean radius of  ellipsoid
} WMMtype_Ellipsoid;

typedef struct
{
    double lambda;      // longitude
    double phi;         // geodetic latitude
    double HeightAboveEllipsoid;        // height above the ellipsoid (HaE)
} WMMtype_CoordGeodetic;

typedef struct
{
    double lambda;      // longitude
    double phig;        // geocentric latitude
    double r;           // distance from the center of the ellipsoid
} WMMtype_CoordSpherical;

typedef struct
{
    int Year;
    int Month;
    int Day;
    double DecimalYear;
} WMMtype_Date;

typedef struct
{
    double Pcup[WMM_NUMPCUP];   // Legendre Function
    double dPcup[WMM_NUMPCUP];  // Derivative of Lagendre fn
} WMMtype_LegendreFunction;

typedef struct
{
    double Bx;          // North
    double By;          // East
    double Bz;          // Down
} WMMtype_MagneticResults;

typedef struct
{
    double RelativeRadiusPower[WMM_MAX_MODEL_DEGREES + 1];      // [earth_reference_radius_km / sph. radius ]^n
    double cos_mlambda[WMM_MAX_MODEL_DEGREES + 1];          // cp(m)  - cosine of (m*spherical coord. longitude
    double sin_mlambda[WMM_MAX_MODEL_DEGREES + 1];          // sp(m)  - sine of (m*spherical coord. longitude)
} WMMtype_SphericalHarmonicVariables;

typedef struct
{
    double Decl;                /*1. Angle between the magnetic field vector and true north, positive east */
    double Incl;                /*2. Angle between the magnetic field vector and the horizontal plane, positive down */
    double F;           /*3. Magnetic Field Strength */
    double H;           /*4. Horizontal Magnetic Field Strength */
    double X;           /*5. Northern component of the magnetic field vector */
    double Y;           /*6. Eastern component of the magnetic field vector */
    double Z;           /*7. Downward component of the magnetic field vector */
    double GV;          /*8. The Grid Variation */
    double Decldot;             /*9. Yearly Rate of change in declination */
    double Incldot;             /*10. Yearly Rate of change in inclination */
    double Fdot;                /*11. Yearly rate of change in Magnetic field strength */
    double Hdot;                /*12. Yearly rate of change in horizontal field strength */
    double Xdot;                /*13. Yearly rate of change in the northern component */
    double Ydot;                /*14. Yearly rate of change in the eastern component */
    double Zdot;                /*15. Yearly rate of change in the downward component */
    double GVdot;               /*16. Yearly rate of chnage in grid variation */
} WMMtype_GeoMagneticElements;

// ******************************

namespace Utils {

    class QTCREATOR_UTILS_EXPORT WorldMagModel
    {
        public:
            WorldMagModel();

            int GetMagVector(double LLA[3], int Month, int Day, int Year, double Be[3]);

        private:
            WMMtype_Ellipsoid       Ellip;
            WMMtype_MagneticModel   MagneticModel;

            double                  decimal_date;

            void Initialize();
            int Geomag(WMMtype_CoordSpherical *CoordSpherical, WMMtype_CoordGeodetic *CoordGeodetic, WMMtype_GeoMagneticElements *GeoMagneticElements);
            void ComputeSphericalHarmonicVariables(WMMtype_CoordSpherical *CoordSpherical, int nMax, WMMtype_SphericalHarmonicVariables *SphVariables);
            int AssociatedLegendreFunction(WMMtype_CoordSpherical *CoordSpherical, int nMax, WMMtype_LegendreFunction *LegendreFunction);
            void Summation(  WMMtype_LegendreFunction *LegendreFunction,
                             WMMtype_SphericalHarmonicVariables *SphVariables,
                             WMMtype_CoordSpherical *CoordSpherical,
                             WMMtype_MagneticResults *MagneticResults);
            void SecVarSummation(    WMMtype_LegendreFunction *LegendreFunction,
                                     WMMtype_SphericalHarmonicVariables *SphVariables,
                                     WMMtype_CoordSpherical *CoordSpherical,
                                     WMMtype_MagneticResults *MagneticResults);
            void RotateMagneticVector(   WMMtype_CoordSpherical *CoordSpherical,
                                         WMMtype_CoordGeodetic *CoordGeodetic,
                                         WMMtype_MagneticResults *MagneticResultsSph,
                                         WMMtype_MagneticResults *MagneticResultsGeo);
            void CalculateGeoMagneticElements(WMMtype_MagneticResults *MagneticResultsGeo, WMMtype_GeoMagneticElements *GeoMagneticElements);
            void CalculateSecularVariation(WMMtype_MagneticResults *MagneticVariation, WMMtype_GeoMagneticElements *MagneticElements);
            int PcupHigh(double *Pcup, double *dPcup, double x, int nMax);
            void PcupLow(double *Pcup, double *dPcup, double x, int nMax);
            void SummationSpecial(WMMtype_SphericalHarmonicVariables *SphVariables, WMMtype_CoordSpherical *CoordSpherical, WMMtype_MagneticResults *MagneticResults);
            void SecVarSummationSpecial(WMMtype_SphericalHarmonicVariables *SphVariables, WMMtype_CoordSpherical *CoordSpherical, WMMtype_MagneticResults *MagneticResults);
            double get_main_field_coeff_g(int index);
            double get_main_field_coeff_h(int index);
            double get_secular_var_coeff_g(int index);
            double get_secular_var_coeff_h(int index);
            int DateToYear(int month, int day, int year);
            void GeodeticToSpherical(WMMtype_CoordGeodetic *CoordGeodetic, WMMtype_CoordSpherical *CoordSpherical);
    };

}

// ******************************

#endif