Function calculate_pole 

pub fn calculate_pole<T: Float>(
    lat: Angle<T>,
    lon: Angle<T>,
    azi: Angle<T>,
) -> Vector3<T>

Calculate the right hand pole vector of a Great Circle from an initial position and an azimuth.

See: http://www.movable-type.co.uk/scripts/latlong-vectors.html#distance

• lat - start point Latitude.
• lon - start point Longitude.
• azi - start point azimuth.

returns the right hand pole vector of the great circle.