LibrePilot/flight/libraries/inc/WMMInternal.h

/**
 ******************************************************************************
 *
 * @file       WMMInternal.h
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * @brief      Include file of the WorldMagModel internal functionality.
 *
 * @see        The GNU Public License (GPL) Version 3
 *
 *****************************************************************************/
/*
 * 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, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#ifndef WMMINTERNAL_H_
#define WMMINTERNAL_H_
#include <pios_math.h>

// internal constants
#define TRUE                                    ((uint16_t)1)
#define FALSE                                   ((uint16_t)0)
#define WMM_MAX_MODEL_DEGREES                   12
#define WMM_MAX_SECULAR_VARIATION_MODEL_DEGREES 12
#define NUMTERMS                                91             // ((WMM_MAX_MODEL_DEGREES+1)*(WMM_MAX_MODEL_DEGREES+2)/2);
#define NUMPCUP                                 92              // NUMTERMS +1
#define NUMPCUPS                                13             // WMM_MAX_MODEL_DEGREES +1

// internal structure definitions
typedef struct {
    float EditionDate;
    float epoch; // Base time of Geomagnetic model epoch (yrs)
    char  ModelName[20];
// float Main_Field_Coeff_G[NUMTERMS];	// C - Gauss coefficients of main geomagnetic model (nT)
// float Main_Field_Coeff_H[NUMTERMS];	// C - Gauss coefficients of main geomagnetic model (nT)
// float Secular_Var_Coeff_G[NUMTERMS];	// CD - Gauss coefficients of secular geomagnetic model (nT/yr)
// float Secular_Var_Coeff_H[NUMTERMS];	// CD - Gauss coefficients of secular geomagnetic model (nT/yr)
    uint16_t nMax; // Maximum degree of spherical harmonic model
    uint16_t nMaxSecVar; // Maxumum degree of spherical harmonic secular model
    uint16_t SecularVariationUsed; // Whether or not the magnetic secular variation vector will be needed by program
} WMMtype_MagneticModel;

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

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

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

typedef struct {
    uint16_t Year;
    uint16_t Month;
    uint16_t Day;
    float    DecimalYear;
} WMMtype_Date;

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

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

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

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

// Internal Function Prototypes
void WMM_Set_Coeff_Array();
int WMM_GeodeticToSpherical(WMMtype_CoordGeodetic *CoordGeodetic, WMMtype_CoordSpherical *CoordSpherical);
int WMM_DateToYear(uint16_t month, uint16_t day, uint16_t year);
int WMM_Geomag(WMMtype_CoordSpherical *CoordSpherical,
               WMMtype_CoordGeodetic *CoordGeodetic, WMMtype_GeoMagneticElements *GeoMagneticElements);

int WMM_AssociatedLegendreFunction(WMMtype_CoordSpherical *CoordSpherical, uint16_t nMax, WMMtype_LegendreFunction *LegendreFunction);

int WMM_CalculateGeoMagneticElements(WMMtype_MagneticResults *MagneticResultsGeo, WMMtype_GeoMagneticElements *GeoMagneticElements);

int WMM_CalculateSecularVariation(WMMtype_MagneticResults *MagneticVariation, WMMtype_GeoMagneticElements *MagneticElements);

int WMM_ComputeSphericalHarmonicVariables(WMMtype_CoordSpherical *
                                          CoordSpherical, uint16_t nMax, WMMtype_SphericalHarmonicVariables *SphVariables);

int WMM_PcupLow(float *Pcup, float *dPcup, float x, uint16_t nMax);

int WMM_PcupHigh(float *Pcup, float *dPcup, float x, uint16_t nMax);

int WMM_RotateMagneticVector(WMMtype_CoordSpherical *,
                             WMMtype_CoordGeodetic *CoordGeodetic,
                             WMMtype_MagneticResults *MagneticResultsSph, WMMtype_MagneticResults *MagneticResultsGeo);

int WMM_SecVarSummation(WMMtype_LegendreFunction *LegendreFunction,
                        WMMtype_SphericalHarmonicVariables *
                        SphVariables, WMMtype_CoordSpherical *CoordSpherical, WMMtype_MagneticResults *MagneticResults);

int WMM_SecVarSummationSpecial(WMMtype_SphericalHarmonicVariables *
                               SphVariables, WMMtype_CoordSpherical *CoordSpherical, WMMtype_MagneticResults *MagneticResults);

int WMM_Summation(WMMtype_LegendreFunction *LegendreFunction,
                  WMMtype_SphericalHarmonicVariables *SphVariables,
                  WMMtype_CoordSpherical *CoordSpherical, WMMtype_MagneticResults *MagneticResults);

int WMM_SummationSpecial(WMMtype_SphericalHarmonicVariables *
                         SphVariables, WMMtype_CoordSpherical *CoordSpherical, WMMtype_MagneticResults *MagneticResults);

float WMM_get_main_field_coeff_g(uint16_t index);
float WMM_get_main_field_coeff_h(uint16_t index);
float WMM_get_secular_var_coeff_g(uint16_t index);
float WMM_get_secular_var_coeff_h(uint16_t index);

#endif /* WMMINTERNAL_H_ */