[ferret_users] return the grid (latitude) for uneven grid

[yangxing zheng <yangxingz@xxxxxxxxx>]

Hi,

   How can we get the exact latitude for calculating f Coriolis paramenter f=2*omega*sin(phi) in a uneven grid, where phi is the latitude. If the grid is even, then f is easily computed.

   In other words, how can get phi from a given uneven grid?

   Thanks.

   Yangxing