code: public static double sphericalVincentyFormulaDeg(double lat1, double lon1, double lat2, double lon2) {
      return sphericalVincentyFormulaRad(deg2rad(lat1), deg2rad(lon1), deg2rad(lat2), deg2rad(lon2));
    }
docs: Compute the approximate great-circle distance of two points.
  
  Uses Vincenty's Formula for the spherical case, which does not require
  iterations.
  <p>
  Complexity: 7 trigonometric functions, 1 sqrt.
  <p>
  Reference:
  <p>
  T. Vincenty<br>
  Direct and inverse solutions of geodesics on the ellipsoid with application
  of nested equations<br>
  Survey Review 23:176, 1975
  
  @param lat1 Latitude of first point in degree
  @param lon1 Longitude of first point in degree
  @param lat2 Latitude of second point in degree
  @param lon2 Longitude of second point in degree
  @return Distance in radians / on unit sphere.