Program Listing for File ellipsoid.h

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#ifndef GEODESY__ELLIPSOID_H_
#define GEODESY__ELLIPSOID_H_

#include <cmath>

namespace geodesy
{
template < typename EllipsoidParameters >
class Ellipsoid
{
public:
  using Parameters = EllipsoidParameters;

  static double M(double latitude)
  {
    return Parameters::a * (1.0 - Parameters::e2) /
            pow((1.0 - Parameters::e2) * pow(sin(latitude), 2.0), 3.0 / 2.0);
  }

  static double N(double latitude)
  {
    if(Parameters::e2 == 0.0) {
      return Parameters::a;
    }
    return Parameters::a / sqrt(1 - Parameters::e2 * pow(sin(latitude), 2.0));
  }

  static inline double longitudinal_span(double latitude, double distance)
  {
    // U is 'reduced latitude'
    double tanU1 = (1.0 - Parameters::f) * tan(latitude);
    double cosU1 = 1 / sqrt(1 + tanU1 * tanU1);
    return distance / (Parameters::a * cosU1);
  }

  static inline double latitudinal_span(double latitude, double distance)
  {
    return distance * pow(1.0 - Parameters::e2 * pow(sin(latitude), 2),
      3.0 / 2.0) / (Parameters::a * (1 - Parameters::e2));
  }
};

}  // namespace geodesy

#endif  // GEODESY__ELLIPSOID_H_