Compute the position and direction of the sun at a given time, on a given date.

Input parameters:

1. Sk → A sphere representing the dome of the sky. The sphere's x-axis points to the East while the y-axis points to the North.
2. Ti → Date and time for the sun's position.
3. La → Latitude of position.
4. Lo → Longitude of position.

Output parameters:

1. Pt → The position of the sun on the sky.
2. Dr → The direction of the sun's light.