This packages is designed for the bathymetric model design and test.
The gravity anomaly is caused by the fluctuation of several density interfaces. Given the
altitudes of these interfaces and the density assumption between those interfaces, the
vertical gravity anomalies shall be obtained, which is implied as the forward process in
the Software. On the other hand, given the vertical gravity anomalies, some fluctuation of
density interfaces shall be determined, which is implied as the inverse process in the
Software.