/// <summary>
/// 常规高程无关球谐函数，如获取高程或深度，电离层电子数等。
/// </summary>
/// <param name="nMax"></param>
/// <param name="lambda_rad"></param>
/// <param name="phi_rad"> 地心纬度</param>
/// <returns></returns>
private double GetCommon2DSphericalHarmonicsValue(int nMax, double lambda_rad, double phi_rad)
{
//转换为天顶距
// double theta_rad = Math.PI / 2 - phi_rad;
double theta_rad = Math.PI / 2 - phi_rad;
FastLegendreCalculater leg = new FastLegendreCalculater(theta_rad);
double val = 0;
for (int n = File.FirstKey; n <= nMax; n++)
{
var latter = HarmonicsSuperposition(n, lambda_rad, theta_rad, leg);
val += latter;
}
return(val);
}
/// <summary>
/// 球谐函数迭代
/// </summary>
/// <param name="theta_rad">rad</param>
/// <param name="n"></param>
/// <param name="lambda">rad</param>
/// <param name="leg">rad，勒让德直接取值</param>
/// <returns></returns>
private double HarmonicsSuperposition(int n, double lambda, double theta_rad, FastLegendreCalculater leg)
{
double val = 0;
var nStep = File[n];
double[] legs = FastLegendreCalculater.Leg(n, theta_rad);
for (int m = 0; m <= n; m++)
{
double Cnm = nStep.C[m].Value;
double Snm = nStep.S[m].Value;
var former = GetItemValue(Cnm, Snm, lambda, m);
var latter = legs[m];
val += former * latter;
}
return(val);
}
/// <summary>
/// 前面的迭代
/// </summary>
/// <param name="nMax"></param>
/// <param name="lambda_rad"></param>
/// <param name="phi_rad">地心纬度</param>
/// <param name="r"></param>
/// <returns></returns>
private double FirstSuperposition(int nMax, double lambda_rad, double phi_rad, double r)
{
//转换为天顶距
double val = 0;
double adivr = a / r;
double theta_rad = Math.PI / 2 - phi_rad;
FastLegendreCalculater leg = new FastLegendreCalculater(theta_rad);
for (int n = File.FirstKey; n <= nMax; n++)
{
var former = Math.Pow(adivr, n);
var latter = HarmonicsSuperposition(n, lambda_rad, theta_rad, leg);
val += former * latter;
}
return(val);
}