public bool TryCalculate(IPosition position, DateTime utcDate, out GeomagnetismResult result)
{
var coordinate = position.GetCoordinate();
var coordinateZ = coordinate as CoordinateZ ?? new CoordinateZ(coordinate.Latitude, coordinate.Longitude, 0);
double lat = coordinateZ.Latitude.ToRadians(),
lon = coordinateZ.Longitude.ToRadians(),
ele = coordinateZ.Elevation / 1000,
dat = JulianDate.JD(utcDate);
var model = _models.SingleOrDefault(mod => mod.ValidFrom <= utcDate && mod.ValidTo > utcDate);
if (model == null)
{
result = default(GeomagnetismResult);
return(false);
}
var bound = 1 + model.MainCoefficientsG.GetUpperBound(0);
var sinLat = Math.Sin(lat);
var cosLat = Math.Cos(lat);
var a = _spheroid.EquatorialAxis / 1000;
var f = _spheroid.Flattening;
var b = a * (1.0 - f);
var sinLat2 = sinLat * sinLat;
var cosLat2 = cosLat * cosLat;
var a2 = a * a;
var a4 = a2 * a2;
var b2 = b * b;
var b4 = b2 * b2;
var sr = Math.Sqrt(a2 * cosLat2 + b2 * sinLat2);
var theta = Math.Atan2(cosLat * (ele * sr + a2), sinLat * (ele * sr + b2));
var r = ele * ele + 2.0 * ele * sr + (a4 - (a4 - b4) * sinLat2) / (a2 - (a2 - b2) * sinLat2);
r = Math.Sqrt(r);
var c = Math.Cos(theta);
var s = Math.Sin(theta);
double invS;
if (Math.Abs(s - 0) < double.Epsilon)
{
invS = 1.0 / (s + 1E-08);
}
else
{
invS = 1.0 / (s + 0.0);
}
var p = new double[bound, bound];
var dp = new double[bound, bound];
p[0, 0] = 1;
p[1, 1] = s;
dp[0, 0] = 0;
dp[1, 1] = c;
p[1, 0] = c;
dp[1, 0] = -s;
for (var i = 2; i < bound; i++)
{
var root = Math.Sqrt((2.0 * i - 1) / (2.0 * i));
p[i, i] = p[i - 1, i - 1] * s * root;
dp[i, i] = (dp[i - 1, i - 1] * s + p[i - 1, i - 1] * c) * root;
}
for (var i = 0; i < bound; i++)
{
double i2 = i * i;
for (var j = Math.Max(i + 1, 2); j < bound; j++)
{
var root1 = Math.Sqrt((j - 1) * (j - 1) - i2);
var root2 = 1.0 / Math.Sqrt(j * j - i2);
p[j, i] = (p[j - 1, i] * c * (2.0 * j - 1) - p[j - 2, i] * root1) * root2;
dp[j, i] = ((dp[j - 1, i] * c - p[j - 1, i] * s) * (2.0 * j - 1) - dp[j - 2, i] * root1) * root2;
}
}
double[,] g = new double[bound, bound], h = new double[bound, bound];
double bRadial = 0.0, bTheta = 0.0, bPhi = 0.0;
var fn0 = _spheroid.MeanRadius / 1000 / r;
var fn = fn0 * fn0;
double[] sm = new double[bound], cm = new double[bound];
sm[0] = Math.Sin(0);
cm[0] = Math.Cos(0);
var yearfrac = (dat - JulianDate.JD(model.ValidFrom)) / 365.25;
for (var i = 1; i < bound; i++)
{
sm[i] = Math.Sin(i * lon);
cm[i] = Math.Cos(i * lon);
for (var j = 0; j < bound; j++)
{
g[i, j] = model.MainCoefficientsG[i, j] + yearfrac * model.SecularCoefficientsG[i, j];
h[i, j] = model.MainCoefficientsH[i, j] + yearfrac * model.SecularCoefficientsH[i, j];
}
double c1 = 0, c2 = 0, c3 = 0;
for (var j = 0; j <= i; j++)
{
var c0 = g[i, j] * cm[j] + h[i, j] * sm[j];
c1 += c0 * p[i, j];
c2 += c0 * dp[i, j];
c3 += j * (g[i, j] * sm[j] - h[i, j] * cm[j]) * p[i, j];
}
fn *= fn0;
bRadial += (i + 1) * c1 * fn;
bTheta -= c2 * fn;
bPhi += c3 * fn * invS;
}
var psi = theta - (Math.PI / 2.0 - lat);
var sinPsi = Math.Sin(psi);
var cosPsi = Math.Cos(psi);
var x = -bTheta * cosPsi - bRadial * sinPsi;
var y = bPhi;
var z = bTheta * sinPsi - bRadial * cosPsi;
result = new GeomagnetismResult(coordinateZ, new DateTime(utcDate.Ticks, DateTimeKind.Utc), x, y, z);
return(true);
}
public bool TryCalculate(IPosition position, DateTime utcDate, out GeomagnetismResult result)
{
var coordinate = position.GetCoordinate();
var coordinateZ = coordinate as CoordinateZ ?? new CoordinateZ(coordinate.Latitude, coordinate.Longitude, 0);
double lat = coordinateZ.Latitude.ToRadians(),
lon = coordinateZ.Longitude.ToRadians(),
ele = coordinateZ.Elevation / 1000,
dat = JulianDate.JD(utcDate);
var model = _models.SingleOrDefault(mod => mod.ValidFrom <= utcDate && mod.ValidTo > utcDate);
if (model == null)
{
result = default(GeomagnetismResult);
return false;
}
var bound = 1 + model.MainCoefficientsG.GetUpperBound(0);
var sinLat = Math.Sin(lat);
var cosLat = Math.Cos(lat);
var a = _spheroid.EquatorialAxis / 1000;
var f = _spheroid.Flattening;
var b = a * (1.0 - f);
var sinLat2 = sinLat * sinLat;
var cosLat2 = cosLat * cosLat;
var a2 = a * a;
var a4 = a2 * a2;
var b2 = b * b;
var b4 = b2 * b2;
var sr = Math.Sqrt(a2 * cosLat2 + b2 * sinLat2);
var theta = Math.Atan2(cosLat * (ele * sr + a2), sinLat * (ele * sr + b2));
var r = ele * ele + 2.0 * ele * sr + (a4 - (a4 - b4) * sinLat2) / (a2 - (a2 - b2) * sinLat2);
r = Math.Sqrt(r);
var c = Math.Cos(theta);
var s = Math.Sin(theta);
double invS;
if (Math.Abs(s - 0) < double.Epsilon)
invS = 1.0 / (s + 1E-08);
else
invS = 1.0 / (s + 0.0);
var p = new double[bound, bound];
var dp = new double[bound, bound];
p[0, 0] = 1;
p[1, 1] = s;
dp[0, 0] = 0;
dp[1, 1] = c;
p[1, 0] = c;
dp[1, 0] = -s;
for (var i = 2; i < bound; i++)
{
var root = Math.Sqrt((2.0 * i - 1) / (2.0 * i));
p[i, i] = p[i - 1, i - 1] * s * root;
dp[i, i] = (dp[i - 1, i - 1] * s + p[i - 1, i - 1] * c) * root;
}
for (var i = 0; i < bound; i++)
{
double i2 = i*i;
for (var j = Math.Max(i + 1, 2); j < bound; j++)
{
var root1 = Math.Sqrt((j - 1) * (j - 1) - i2);
var root2 = 1.0 / Math.Sqrt(j * j - i2);
p[j, i] = (p[j - 1, i] * c * (2.0 * j - 1) - p[j - 2, i] * root1) * root2;
dp[j, i] = ((dp[j - 1, i] * c - p[j - 1, i] * s) * (2.0 * j - 1) - dp[j - 2, i] * root1) * root2;
}
}
double[,] g = new double[bound, bound], h = new double[bound, bound];
double bRadial = 0.0, bTheta = 0.0, bPhi = 0.0;
var fn0 = _spheroid.MeanRadius / 1000 / r;
var fn = fn0 * fn0;
double[] sm = new double[bound], cm = new double[bound];
sm[0] = Math.Sin(0);
cm[0] = Math.Cos(0);
var yearfrac = (dat - JulianDate.JD(model.ValidFrom)) / 365.25;
for (var i = 1; i < bound; i++)
{
sm[i] = Math.Sin(i * lon);
cm[i] = Math.Cos(i * lon);
for (var j = 0; j < bound; j++)
{
g[i, j] = model.MainCoefficientsG[i, j] + yearfrac * model.SecularCoefficientsG[i, j];
h[i, j] = model.MainCoefficientsH[i, j] + yearfrac * model.SecularCoefficientsH[i, j];
}
double c1 = 0, c2 = 0, c3 = 0;
for (var j = 0; j <= i; j++)
{
var c0 = g[i, j] * cm[j] + h[i, j] * sm[j];
c1 += c0 * p[i, j];
c2 += c0 * dp[i, j];
c3 += j * (g[i, j] * sm[j] - h[i, j] * cm[j]) * p[i, j];
}
fn *= fn0;
bRadial += (i + 1) * c1 * fn;
bTheta -= c2 * fn;
bPhi += c3 * fn * invS;
}
var psi = theta - (Math.PI / 2.0 - lat);
var sinPsi = Math.Sin(psi);
var cosPsi = Math.Cos(psi);
var x = -bTheta * cosPsi - bRadial * sinPsi;
var y = bPhi;
var z = bTheta * sinPsi - bRadial * cosPsi;
result = new GeomagnetismResult(coordinateZ, new DateTime(utcDate.Ticks, DateTimeKind.Utc), x, y, z);
return true;
}
public bool TryCalculate(IPosition position, DateTimeOffset date, out GeomagnetismResult result)
{
return(TryCalculate(position, date.UtcDateTime, out result));
}
public bool TryCalculate(IPosition position, DateTimeOffset date, out GeomagnetismResult result)
{
return TryCalculate(position, date.UtcDateTime, out result);
}
