/// <summary>
/// 趋近法算角度
/// </summary>
/// <param name="dL">初始经度差</param>
/// <param name="cosu2">cosu2</param>
/// <param name="cosu1">cosu1</param>
/// <param name="ab">ab参数数组</param>
/// <param name="lamda">lamda经度差估计值</param>
/// <param name="A1">A1坐标方位角</param>
/// <param name="del">del</param>
/// <param name="cos2_A0">cos2_A0</param>
/// <param name="x">x</param>
private void CalA1_Lamda(double dL, double u2, double u1, double [] ab, ref double lamda, ref double A1,
ref double del, ref double cos2_A0)
{
double deltat = 0, delta = 0;
double cos_del = 0, sin_del = 0;
double e1 = Ell.e1;
double alpha = 0, beta = 0, gama = 0;
double sinA0;
double p = 0;
double q = 0;
lamda = dL;
do
{
deltat = delta;
p = Math.Cos(u2) * Math.Sin(lamda);
q = ab[2] - ab[3] * Math.Cos(lamda);
A1 = Math.Abs(Math.Atan(p / q));
A1 = GeoPro.InvJudgeA1A2(p, q, A1);
sin_del = p * Math.Sin(A1) + q * Math.Cos(A1);
cos_del = ab[0] + ab[1] * Math.Cos(lamda);
del = Math.Atan(sin_del / cos_del);
del = GeoPro.InvJudgedel(del, cos_del);
sinA0 = Math.Cos(u1) * Math.Sin(A1);
double del1 = Math.Atan(Math.Tan(u1) / Math.Cos(A1));
cos2_A0 = 1 - sinA0 * sinA0;
alpha = GeoPro.GetAlpha(e1, cos2_A0);
beta = GeoPro.GetBeta(e1, cos2_A0);
gama = GeoPro.GetGama(e1, cos2_A0);
delta = (alpha * del + (beta) * Math.Cos(2 * del1 + del) * Math.Sin(del)
+ gama * Math.Sin(2 * del) * Math.Cos(4 * del1 + 2 * del)) * sinA0;
lamda = dL + delta;
} while (Math.Abs(delta - deltat) * 206265 > 0.00001);
}
/// <summary>
/// 单组数据反算
/// </summary>
/// <param name="geodesic">单组大地线数据</param>
public void InverseSolution(GeodesicInfo geodesic)
{
//数据格式转换
double B1 = GeoPro.DMS2RAD(geodesic.P1.B);
double L1 = GeoPro.DMS2RAD(geodesic.P1.L);
double B2 = GeoPro.DMS2RAD(geodesic.P2.B);
double L2 = GeoPro.DMS2RAD(geodesic.P2.L);
double A12 = 0, A21 = 0, S = 0;
//椭球参数
double e1, e2, b, c, a;
e1 = Ell.e1; e2 = Ell.e2;
b = Ell.b; c = Ell.c; a = Ell.a;
//辅助计算
double u1 = Math.Atan(Math.Sqrt(1 - e1 * e1) * Math.Tan(B1));
double u2 = Math.Atan(Math.Sqrt(1 - e1 * e1) * Math.Tan(B2));
double dL = L2 - L1;
double[] ab = CalPara(u1, u2);
if (u1 == 0 && u2 == 0)
{
if (dL > 0)
{
S = a * dL;
A12 = Math.PI / 2;
A21 = Math.PI * 3 / 2;
}
else
{
S = a * dL;
A21 = Math.PI / 2;
A12 = Math.PI * 3 / 2;
}
}
else
{
//逐次趋近法同时计算起点大地方位角，球面长度及经度差lamda
double del = 0;
double lamda = 0;
double cos2_A0 = 0;
CalA1_Lamda(dL, u2, u1, ab, ref lamda, ref A12, ref del, ref cos2_A0);
//计算S
double[] ABC = new double[3];
double k_2 = GeoPro.Getk_2(e2, cos2_A0);
GeoPro.GetABC(b, k_2, ABC);
double del1 = Math.Atan(Math.Tan(u1) / Math.Cos(A12));
double xs12 = ABC[2] * Math.Sin(2 * del) * Math.Cos(4 * del1 + 2 * del);
S = (del - ABC[1] * Math.Sin(del) * Math.Cos(2 * del1 + del) - xs12) / ABC[0];
//计算A2
A21 = Math.Atan(Math.Cos(u1) * Math.Sin(lamda) / (ab[2] * Math.Cos(lamda) - ab[3]));
A21 = GeoPro.InvJudgeA1A2(Math.Cos(u1) * Math.Sin(lamda), (ab[2] * Math.Cos(lamda) - ab[3]), A21);
//
if (A12 >= Math.PI)
{
A21 = A21 - Math.PI;
}
if (A12 < Math.PI)
{
A21 = A21 + Math.PI;
}
}
//
geodesic.A12 = GeoPro.RAD2DMS(A12);
geodesic.A21 = GeoPro.RAD2DMS(A21);
geodesic.S = S;
}
