辅助纬度与大地纬度间的无穷展开

利用无穷级数理论和拉格朗日反演定理,详细推导了大地测量和制图学中常用的辅助纬度与大地纬度间的无穷展开,主要表现为参考椭球第一偏心率的幂级数形式。通过建立一系列严格的系数递推公式,得到了等量纬度反解展开式和等角纬度反解展开式;同时,推导了古德曼函数的泰勒展开式,进而得到了等角纬度正解展开式;利用级数除法公式,得到了等距离纬度正解展开式系数的行列式表示。通过比较本文方法与计算机代数系统Mathematica直接推导求得的辅助纬度正反解展开式e^0～e⁴⁰阶系数和相应的程序用时,表明本文算法是正确的、快速的。以CGCS2000参考椭球为例,对辅助纬度正反解进行了算例分析,也进一步验证了本文公式的正确性。

Infinite expansions of the auxiliary latitudes with respect to the geodetic latitude

By using the theory of infinite series and the Lagrange inversion theorem, the infinite expansions of the auxiliary latitudes in geodesy and cartography with respect to the geodetic latitude are given, which are the power series of the first eccentricity of the reference ellipsoid. The inverse solutions of the isometric and the conformal latitudes can be obtained from the recurrences of a number of known coefficients. The forward expansion of the conformal latitude is proposed on the basis of the Taylor expansion of the Gudermannian function, and the forward expansion of the rectifying latitude is given in which the coefficient can be expressed as a explicit determinant by the division of power series. Compared the coefficients of the auxiliary latitudes expansions at order e⁰ to e⁴⁰ with the results by the computer algebra system Mathematica and the corresponding cost time, the algorithm of this paper is verified to be correct and fast. By taking CGCS2000 reference ellipsoid, the numerical experiment is made for the expansions and then the correctness is further proved.