public GeoMagVector(GeoMagVector other)
{
d = other.d;
s = other.s;
h = other.h;
x = other.x;
y = other.y;
z = other.z;
f = other.f;
}
/// <summary>
/// Subtracts one vector from another
/// </summary>
/// <param name="vector2">The vector which to subtract</param>
/// <returns>A vector containing the result of the subtraction</returns>
public GeoMagVector Subtract(GeoMagVector vector2)
{
return(new GeoMagVector
{
d = d - vector2.d,
s = s - vector2.s,
h = h - vector2.h,
x = x - vector2.x,
y = y - vector2.y,
z = z - vector2.z,
f = f - vector2.f
});
}
public MagneticCalculations(DateTime inDate, GeoMagVector fieldCalculations, GeoMagVector SecVarCalculations = null)
{
Date = inDate;
Declination = new MagneticValue
{
Value = fieldCalculations.d,
ChangePerYear = SecVarCalculations == null ? 0 : SecVarCalculations.d
};
Inclination = new MagneticValue
{
Value = fieldCalculations.s,
ChangePerYear = SecVarCalculations == null ? 0 : SecVarCalculations.s
};
HorizontalIntensity = new MagneticValue
{
Value = fieldCalculations.h,
ChangePerYear = SecVarCalculations == null ? 0 : SecVarCalculations.h
};
NorthComp = new MagneticValue
{
Value = fieldCalculations.x,
ChangePerYear = SecVarCalculations == null ? 0 : SecVarCalculations.x
};
EastComp = new MagneticValue
{
Value = fieldCalculations.y,
ChangePerYear = SecVarCalculations == null ? 0 : SecVarCalculations.y
};
VerticalComp = new MagneticValue
{
Value = fieldCalculations.z,
ChangePerYear = SecVarCalculations == null ? 0 : SecVarCalculations.z
};
TotalField = new MagneticValue
{
Value = fieldCalculations.f,
ChangePerYear = SecVarCalculations == null ? 0 : SecVarCalculations.f
};
}
/// <summary>
/// calculate main field and field change at a 'spot' in time and space
/// </summary>
/// <param name="CalculationOptions">details of the time and space to for which to calculate</param>
/// <param name="dateOfCalc">The DateTime object for the calculation date</param>
/// <param name="magModels">the models loaded by the Model Reader</param>
/// <param name="internalSH">internal coeffiecients for a particular date</param>
/// <param name="externalSH">external coeffiecients for a particular date</param>
/// <param name="earthRadius">Optional: Radius of the earth used by the model</param>
/// <returns>The result of the magnetic calculation</returns>
public static MagneticCalculations SpotCalculation(CalculationOptions CalculationOptions, DateTime dateOfCalc, MagneticModelSet magModels,
Coefficients internalSH, Coefficients externalSH, double earthRadius = Constants.EarthsRadiusInKm)
{
/* call procedure GETFIELD - values returned in geomagfield*/
var fieldCalculations = GetField(CalculationOptions, internalSH, externalSH, earthRadius);
GeoMagVector svCalculations = null;
if (CalculationOptions.SecularVariation)
{
double date1 = -1;
double date2 = -1;
CalculateDatesForVariation(CalculationOptions.StartDate.ToDecimal(), magModels.MinDate, magModels.MaxDate, out date1, out date2);
/* get coefficients and field for date1 */
var SVintSH = new Coefficients();
var SVextSH = new Coefficients();
magModels.GetIntExt(date1, out SVintSH, out SVextSH);
var geomagfield1 = GetField(CalculationOptions, SVintSH, SVextSH, earthRadius);
/* get coefficients and field for date2 */
magModels.GetIntExt(date2, out SVintSH, out SVextSH);
var geomagfield2 = GetField(CalculationOptions, SVintSH, SVextSH, earthRadius);
/* calculate changes - difference between
* fields 1 & 2 returned in fielddiffs */
svCalculations = geomagfield2.Subtract(geomagfield1);
} /* end of secular variation calc. for SPOT */
return(new MagneticCalculations(dateOfCalc, fieldCalculations, svCalculations));
}
private static GeoMagVector GetField(CalculationOptions CalculationOptions, Coefficients internalSH, Coefficients externalSH, double er_rad)
{
/* allocate storage for arrays */
Int32 kmx = (internalSH.MaxDegree + 1) * (internalSH.MaxDegree + 2) / 2;
Int32 isize = internalSH.MaxDegree * (internalSH.MaxDegree + 2);
Int32 esize = externalSH.MaxDegree * (externalSH.MaxDegree + 2);
Int32 nagh = isize + esize;
var agh = new double[nagh];
var zmn = new double[2 * isize];
var xmn = new double[2 * isize];
var ymn = new double[2 * isize];
var cl = new double[isize];
var sl = new double[isize];
var p = new double[kmx];
var q = new double[kmx];
/* set values of agh */
for (Int32 aghIdx = 0; aghIdx < nagh; aghIdx++)
{
if (aghIdx < isize)
{
agh[aghIdx] = internalSH.coeffs[aghIdx];
}
else
{
agh[aghIdx] = externalSH.coeffs[aghIdx - isize];
}
} /* end of setting agh */
double altitude = CalculationOptions.AltitudeInKm;
double gcCoLat = 0;
double earthRadius = 0;
double cd = 0;
double sd = 0;
GeodeticToGeocentric(CalculationOptions.CoLatitude, altitude, out gcCoLat, out earthRadius, out cd, out sd);
double one = gcCoLat;
double slat = Math.Cos(one.ToRadian());
double clat = Math.Sin(one.ToRadian());
one = CalculationOptions.Longitude;
cl[0] = (Math.Cos(one.ToRadian()));
sl[0] = (Math.Sin(one.ToRadian()));
var geomagfield = new GeoMagVector();
/* printf("GETFIELD 2: %lf %lf %lf %lf\n", slat, clat, cl[0],sl[0]); */
/****Computation of the spherical harmonics using
* Schmidt quasi-normal Legendre polynomials p and q **/
Int32 li = 0;
Int32 le = isize;
Int32 m = 0;
Int32 n = -1;
/* reference radius */
double ratio = er_rad / earthRadius;
double rri = ratio * ratio;
double rre = ratio;
p[0] = 1.0;
p[2] = clat;
q[0] = 0.0;
q[2] = slat;
double fn = 0;
double gn = 0;
double fm = 0;
double two = 0;
double three = 0;
Int32 i = 0;
Int32 j = 0;
for (Int32 k = 1; k < kmx; k++, m++)
{
if (n < m)
{
m = -1;
n++;
rri = rri * ratio;
rre = rre / ratio;
fn = n + 1;
gn = n;
}
fm = m + 1;
if (n != m)
{
/** block 3 **/
one = Math.Sqrt(fn * fn - fm * fm);
two = Math.Sqrt(gn * gn - fm * fm) / one;
three = (fn + gn) / one;
i = k - n - 1;
j = k - 2 * (n + 1) + 1;
p[k] = three * slat * p[i] - two * p[j];
q[k] = three * (slat * q[i] - clat * p[i]) - two * q[j];
}
else if (k != 2)
{
/** block 2 **/
one = Math.Sqrt(1.0 - 0.5 / fm);
j = k - n - 2;
p[k] = one * clat * p[j];
q[k] = one * (clat * q[j] + slat * p[j]);
sl[m] = sl[m - 1] * cl[0] + cl[m - 1] * sl[0];
cl[m] = cl[m - 1] * cl[0] - sl[m - 1] * sl[0];
}
if (m < 0)
{
/** block 4 **/
zmn[li] = -(fn + 1.0) * p[k] * rri;
zmn[le] = fn * p[k] * rre;
xmn[li] = q[k] * rri;
ymn[li] = 0.0;
xmn[le] = q[k] * rre;
ymn[le] = 0.0;
li++;
le++;
}
else
{ /* m >= 0 */
/**block 5**/
zmn[li] = -(fn + 1.0) * p[k] * rri * cl[m];
xmn[li] = q[k] * rri * cl[m];
zmn[le] = fn * p[k] * rre * cl[m];
xmn[le] = q[k] * rre * cl[m];
if (clat != 0)
{
ymn[li] = fm * p[k] / clat * rri * sl[m];
ymn[le] = fm * p[k] / clat * rre * sl[m];
}
else
{
ymn[li] = q[k] * slat * rri * sl[m];
ymn[le] = q[k] * slat * rre * sl[m];
}
/**block 8 **/
li++;
le++;
zmn[li] = -(fn + 1.0) * p[k] * rri * sl[m];
xmn[li] = q[k] * rri * sl[m];
zmn[le] = fn * p[k] * rre * sl[m];
xmn[le] = q[k] * rre * sl[m];
if (clat != 0)
{
ymn[li] = -fm * p[k] / clat * rri * cl[m];
ymn[le] = -fm * p[k] / clat * rre * cl[m];
}
else
{
ymn[li] = -q[k] * slat * rri * cl[m];
ymn[le] = -q[k] * slat * rre * cl[m];
}
/** block 10 **/
li++;
le++;
} /* end of if statement for m<=0 */
} /* end of for loop */
for (i = 0; i < 2 * isize; i++)
{
if (i >= nagh)
{
xmn[i] = 0.0;
ymn[i] = 0.0;
zmn[i] = 0.0;
}
else
{
geomagfield.x += xmn[i] * agh[i];
geomagfield.y += ymn[i] * agh[i];
geomagfield.z += zmn[i] * agh[i];
}
} /* end of for loop assigning geomagfield */
/* convert x and z into geodetic coordinate system */
one = geomagfield.x;
geomagfield.x = (geomagfield.x) * cd + (geomagfield.z) * sd;
geomagfield.z = (geomagfield.z) * cd - one * sd;
/* compute remaining elements */
geomagfield.d = Math.Atan2(geomagfield.y, geomagfield.x).ToDegree();
geomagfield.h = Math.Sqrt(geomagfield.x * geomagfield.x + geomagfield.y * geomagfield.y);
geomagfield.s = Math.Atan2(geomagfield.z, geomagfield.h).ToDegree();
geomagfield.f = Math.Sqrt(geomagfield.x * geomagfield.x + geomagfield.y * geomagfield.y + geomagfield.z * geomagfield.z);
return(geomagfield);
}
