Index: trunk/GnssCenter/map_stations/const.cpp
===================================================================
--- trunk/GnssCenter/map_stations/const.cpp	(revision 5437)
+++ trunk/GnssCenter/map_stations/const.cpp	(revision 5437)
@@ -0,0 +1,4 @@
+#include "const.h"
+
+const double t_CST::aell    = 6378137.000;
+const double t_CST::fInv    = 298.2572236;
Index: trunk/GnssCenter/map_stations/const.h
===================================================================
--- trunk/GnssCenter/map_stations/const.h	(revision 5437)
+++ trunk/GnssCenter/map_stations/const.h	(revision 5437)
@@ -0,0 +1,13 @@
+#ifndef CONST_H
+#define CONST_H
+
+enum t_irc {failure = -1, success, fatal}; // return code
+
+class t_CST {
+ public:
+  static const double aell;
+  static const double fInv;
+};
+
+
+#endif
Index: trunk/GnssCenter/map_stations/map_stations.pro
===================================================================
--- trunk/GnssCenter/map_stations/map_stations.pro	(revision 5436)
+++ trunk/GnssCenter/map_stations/map_stations.pro	(revision 5437)
@@ -25,8 +25,12 @@
 
 HEADERS   = map_stations.h \
+            utils.h        \
+            const.h        \
             worldplot.h    \
             thriftclient.h 
 
 SOURCES   = map_stations.cpp \
+            utils.cpp        \
+            const.cpp        \
             worldplot.cpp    \
             thriftclient.cpp \
Index: trunk/GnssCenter/map_stations/utils.cpp
===================================================================
--- trunk/GnssCenter/map_stations/utils.cpp	(revision 5437)
+++ trunk/GnssCenter/map_stations/utils.cpp	(revision 5437)
@@ -0,0 +1,86 @@
+
+#include <math.h>
+
+#include "utils.h"
+
+using namespace std;
+
+// Rectangular Coordinates -> Ellipsoidal Coordinates
+////////////////////////////////////////////////////////////////////////////
+t_irc xyz2ell(const double* XYZ, double* Ell) {
+
+  const double bell = t_CST::aell*(1.0-1.0/t_CST::fInv) ;
+  const double e2   = (t_CST::aell*t_CST::aell-bell*bell)/(t_CST::aell*t_CST::aell) ;
+  const double e2c  = (t_CST::aell*t_CST::aell-bell*bell)/(bell*bell) ;
+  
+  double nn, ss, zps, hOld, phiOld, theta, sin3, cos3;
+
+  ss    = sqrt(XYZ[0]*XYZ[0]+XYZ[1]*XYZ[1]) ;
+  zps   = XYZ[2]/ss ;
+  theta = atan( (XYZ[2]*t_CST::aell) / (ss*bell) );
+  sin3  = sin(theta) * sin(theta) * sin(theta);
+  cos3  = cos(theta) * cos(theta) * cos(theta);
+
+  // Closed formula
+  Ell[0] = atan( (XYZ[2] + e2c * bell * sin3) / (ss - e2 * t_CST::aell * cos3) );  
+  Ell[1] = atan2(XYZ[1],XYZ[0]) ;
+  nn = t_CST::aell/sqrt(1.0-e2*sin(Ell[0])*sin(Ell[0])) ;
+  Ell[2] = ss / cos(Ell[0]) - nn;
+
+  const int MAXITER = 100;
+  for (int ii = 1; ii <= MAXITER; ii++) {
+    nn     = t_CST::aell/sqrt(1.0-e2*sin(Ell[0])*sin(Ell[0])) ;
+    hOld   = Ell[2] ;
+    phiOld = Ell[0] ;
+    Ell[2] = ss/cos(Ell[0])-nn ;
+    Ell[0] = atan(zps/(1.0-e2*nn/(nn+Ell[2]))) ;
+    if ( fabs(phiOld-Ell[0]) <= 1.0e-11 && fabs(hOld-Ell[2]) <= 1.0e-5 ) {
+      return success;
+    }
+  }
+
+  return failure;
+}
+
+// Rectangular Coordinates -> North, East, Up Components
+////////////////////////////////////////////////////////////////////////////
+void xyz2neu(const double* Ell, const double* xyz, double* neu) {
+
+  double sinPhi = sin(Ell[0]);
+  double cosPhi = cos(Ell[0]);
+  double sinLam = sin(Ell[1]);
+  double cosLam = cos(Ell[1]);
+
+  neu[0] = - sinPhi*cosLam * xyz[0]
+           - sinPhi*sinLam * xyz[1]
+           + cosPhi        * xyz[2];
+
+  neu[1] = - sinLam * xyz[0]
+           + cosLam * xyz[1];
+
+  neu[2] = + cosPhi*cosLam * xyz[0]
+           + cosPhi*sinLam * xyz[1]
+           + sinPhi        * xyz[2];
+}
+
+// North, East, Up Components -> Rectangular Coordinates
+////////////////////////////////////////////////////////////////////////////
+void neu2xyz(const double* Ell, const double* neu, double* xyz) {
+
+  double sinPhi = sin(Ell[0]);
+  double cosPhi = cos(Ell[0]);
+  double sinLam = sin(Ell[1]);
+  double cosLam = cos(Ell[1]);
+
+  xyz[0] = - sinPhi*cosLam * neu[0]
+           - sinLam        * neu[1]
+           + cosPhi*cosLam * neu[2];
+
+  xyz[1] = - sinPhi*sinLam * neu[0]
+           + cosLam        * neu[1]
+           + cosPhi*sinLam * neu[2];
+
+  xyz[2] = + cosPhi        * neu[0]
+           + sinPhi        * neu[2];
+}
+
Index: trunk/GnssCenter/map_stations/utils.h
===================================================================
--- trunk/GnssCenter/map_stations/utils.h	(revision 5437)
+++ trunk/GnssCenter/map_stations/utils.h	(revision 5437)
@@ -0,0 +1,12 @@
+#ifndef UTILS_H
+#define UTILS_H
+
+#include "const.h"
+
+t_irc xyz2ell(const double* XYZ, double* Ell);
+
+void xyz2neu(const double* Ell, const double* xyz, double* neu);
+
+void neu2xyz(const double* Ell, const double* neu, double* xyz);
+
+#endif