中文摘要：

在利用坐标反算方位角的反正弦、反余弦和反正切公式的基础上,本文给出了反正弦公式的C语言程序,又利用方位角的特性,构造了方位角排序算法,即半圆周排序和圆周排序算法。然后,将坐标反算求取方位角公式应用到了空间方向描述之中,并且将半圆周排序算法应用在了多边形面积计算中,圆周排序法应用在Voronoi图的构建之中。实验证明该坐标反算公式和两种排序算法在GIS图形算法研究方面很有实用价值。

英文摘要：

Basing on the detailed introduction of the coordinate-inverse calculation formnlas, such as arc-sine formula, arc-cosine formala and arc-tangent formula, this paper showed the programs of arc-sine formula by C language. In the same time, it constructed the sort algorithm, namely half-circle sort algorithm and circle sort algorithm, by using the speciality of azimuth angle. Then the authors applied the fo~mlas of coordinate-inverse calculation to the spatial direction description, and the half-circle sort algorithm to calculation of polygon＇s area as well. And circle sort algorithm was used to draw Voronoi diagram. It was proved that the methods of calculation and the two sort algorithms were appliable in the study of GIS graphs.