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// Example of using the GeographicLib::MagneticCircle class
// This requires that the wmm2010 magnetic model be installed; see
// https://geographiclib.sourceforge.io/C++/doc/magnetic.html#magneticinst
#include <iostream>
#include <exception>
#include <GeographicLib/MagneticModel.hpp>
#include <GeographicLib/MagneticCircle.hpp>
using namespace std;
using namespace GeographicLib;
int main() {
try {
MagneticModel mag("wmm2010");
double lat = 27.99, lon0 = 86.93, h = 8820, t = 2012; // Mt Everest
{
// Slow method of evaluating the values at several points on a circle of
// latitude.
for (int i = -5; i <= 5; ++i) {
double lon = lon0 + i * 0.2;
double Bx, By, Bz;
mag(t, lat, lon, h, Bx, By, Bz);
cout << lon << " " << Bx << " " << By << " " << Bz << "\n";
}
}
{
// Fast method of evaluating the values at several points on a circle of
// latitude using MagneticCircle.
MagneticCircle circ = mag.Circle(t, lat, h);
for (int i = -5; i <= 5; ++i) {
double lon = lon0 + i * 0.2;
double Bx, By, Bz;
circ(lon, Bx, By, Bz);
cout << lon << " " << Bx << " " << By << " " << Bz << "\n";
}
}
}
catch (const exception& e) {
cerr << "Caught exception: " << e.what() << "\n";
return 1;
}
}
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