https://b.hatena.ne.jp/entry/s/mathworld.wolfram.com/SphericalCoordinates.html Spherical coordinates, also called spherical polar coordinates (Walton 1967, Arfken 1985), are a system of curvilinear coordinates that are natural for describing positions on a sphere or spheroid.... https://b.hatena.ne.jp/schrift/20100606#bookmark-5057453 2010-06-05T17:40:56Z https://b.hatena.ne.jp/nilab/20070620#bookmark-5057453 Spherical Coordinates -- from Wolfram MathWorld 2007-06-20T08:14:26Z math sphere