// Example of using the GeographicLib::CircularEngine class

#include <iostream>
#include <exception>
#include <vector>
#include <GeographicLib/CircularEngine.hpp>
#include <GeographicLib/SphericalHarmonic.hpp>

using namespace std;
using namespace GeographicLib;

int main() {
 // This computes the same value as example-SphericalHarmonic.cpp using a
 // CircularEngine (which will be faster if many values on a circle of
 // latitude are to be found).
 try {
 int N = 3; // The maxium degree
 double ca[] = {10, 9, 8, 7, 6, 5, 4, 3, 2, 1}; // cosine coefficients
 vector<double> C(ca, ca + (N + 1) * (N + 2) / 2);
 double sa[] = {6, 5, 4, 3, 2, 1}; // sine coefficients
 vector<double> S(sa, sa + N * (N + 1) / 2);
 double a = 1;
 SphericalHarmonic h(C, S, N, a);
 double x = 2, y = 3, z = 1, p = Math::hypot(x, y);
 CircularEngine circ = h.Circle(p, z, true);
 double v, vx, vy, vz;
 v = circ(x/p, y/p, vx, vy, vz);
 cout << v << " " << vx << " " << vy << " " << vz << "\n";
 }
 catch (const exception& e) {
 cerr << "Caught exception: " << e.what() << "\n";
 return 1;
 }
}