Adding and modify many useful function

in their header file:
-blh2enu.h
-xyz2blh.h
-rahcal.h
-deg2dms.h
-degRrad.h

rahcal.h

@@ -0,0 +1,39 @@
+#ifndef _RAHCAL_H_
+#define _RAHCAL_H_
+#define PI 3.141592653589793
+
+
+#include<stdlib.h>
+#include<math.h>
+
+typedef struct 
+{
+    double R;
+    double A;
+    double H;
+}rahcal, *prahcal;
+
+/* -------------------------------------------------------------------------- */
+/// @brief 计算站心坐标系下的卫星高度方位角
+/// @param rahcal 自定义结构体变量用于传参
+/// @param E 站心坐标东
+/// @param N 站心坐标北
+/// @param U 站心坐标天
+/// @return 返回自定义结构体变量包含R, A, H成员                        
+/* -------------------------------------------------------------------------- */
+prahcal RAHCAL(prahcal rahcal, 
+               double E, double N, double U)
+{
+    rahcal = (prahcal)malloc(sizeof(prahcal));
+    rahcal->H = atan2(U, sqrt(E * E + N * N));
+    rahcal->A = atan2(E, U);
+    if (rahcal->A < 0)
+        rahcal->A += 2 * PI;
+    if (rahcal->A > 2 * PI)
+        rahcal->A -= 2 * PI;
+    rahcal->R = sqrt(E * E + N * N + U * U);
+
+    return rahcal;
+}
+
+#endif