Adding and modify many useful function

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

blh2enu.h

@@ -0,0 +1,40 @@
+#ifndef _BLH2ENU_H_
+#define _BLH2ENU_H_
+
+#include<stdlib.h>
+#include<math.h>
+
+typedef struct
+{
+   double E;
+   double N;
+   double U;
+}blh2enu, *pblh2enu;
+
+/* -------------------------------------------------------------------------- */
+/// @brief 将大地高坐标转换为站心坐标
+/// @param blh2enu 自定义结构体类型用来传参
+/// @param stationB 站心纬度
+/// @param stationL 站心经度
+/// @param deltax 卫星到站心的x坐标差值
+/// @param deltay 卫星到站心的y坐标差值
+/// @param deltaz 卫星到站心的z坐标差值
+/// @return 返回自定义结构体类型包含E, N, U成员
+/* -------------------------------------------------------------------------- */
+pblh2enu BLH2ENU(pblh2enu blh2enu, 
+                 double stationB, double stationL,
+                 double deltax, double deltay, double deltaz)
+{
+    double sinB = sin(stationB);
+    double cosB = cos(stationB);
+    double sinL = sin(stationL);
+    double cosL = cos(stationL);
+    blh2enu = (pblh2enu)malloc(sizeof(pblh2enu));
+    blh2enu->E = -     sinL*(deltax) +      cosL*(deltay);
+    blh2enu->N = -sinB*cosL*(deltax) - sinB*sinL*(deltay) + cosB*(deltaz);
+    blh2enu->U =  cosB*cosL*(deltax) + cosB*sinL*(deltay) + sinB*(deltaz);
+
+    return blh2enu;
+}
+
+#endif