To ascertain by mathematics
The Parsees compute time from the fall of Yazdegerd.
As An Example, Suppose It Were Required To Compute Easter For The Year 1840.
Mathematically we have thus in all cases to compute present value on the basis of a deferred as well as a limited annuity.
The third law enables us to compute the time taken by the radius vector to sweep over the entire area of the orbit, which is identical with the time of revolution.
This, and the inclination of the orbit being given, we have all the geometrical data necessary to compute the coordinates of the planet itself.