known as the I<radial> coordinate. The angle in the I<xy>-plane
(around the I<z>-axis) is B<theta>, also known as the I<azimuthal>
coordinate. The angle from the I<z>-axis is B<phi>, also known as the
-I<polar> coordinate. The `North Pole' is therefore I<0, 0, rho>, and
-the `Bay of Guinea' (think of the missing big chunk of Africa) I<0,
+I<polar> coordinate. The North Pole is therefore I<0, 0, rho>, and
+the Gulf of Guinea (think of the missing big chunk of Africa) I<0,
pi/2, rho>. In geographical terms I<phi> is latitude (northward
positive, southward negative) and I<theta> is longitude (eastward
positive, westward negative).