ADD: new track message, Entity class and Position class

libs/geographiclib/examples/make-egmcof.cpp

@@ -0,0 +1,45 @@
+// Write the coefficient files needed for approximating the normal gravity
+// field with a GravityModel.  WARNING: this creates files, wgs84.egm.cof and
+// grs80.egm.cof, in the current directory.
+
+#include <cmath>
+#include <fstream>
+#include <iostream>
+#include <GeographicLib/NormalGravity.hpp>
+#include <GeographicLib/Utility.hpp>
+
+using namespace std;
+using namespace GeographicLib;
+
+int main() {
+  try {
+    Utility::set_digits();
+    const char* filenames[] = {"wgs84.egm.cof", "grs80.egm.cof"};
+    const char* ids[] = {"WGS1984A", "GRS1980A"};
+    for (int grs80 = 0; grs80 < 2; ++grs80) {
+      ofstream file(filenames[grs80], ios::binary);
+      Utility::writearray<char, char, false>(file, ids[grs80], 8);
+      const int N = 20, M = 0,
+        cnum = (M + 1) * (2 * N - M + 2) / 2; // cnum = N + 1
+      vector<int> num(2);
+      num[0] = N; num[1] = M;
+      Utility::writearray<int, int, false>(file, num);
+      vector<Math::real> c(cnum, 0);
+      const NormalGravity& earth(grs80 ? NormalGravity::GRS80() :
+                                 NormalGravity::WGS84());
+      for (int n = 2; n <= N; n += 2)
+        c[n] = - earth.DynamicalFormFactor(n) / sqrt(Math::real(2*n + 1));
+      Utility::writearray<double, Math::real, false>(file, c);
+      num[0] = num[1] = -1;
+      Utility::writearray<int, int, false>(file, num);
+    }
+  }
+  catch (const exception& e) {
+    cerr << "Caught exception: " << e.what() << "\n";
+    return 1;
+  }
+  catch (...) {
+    cerr << "Caught unknown exception\n";
+    return 1;
+  }
+}