how to get partial derivatives from discrete data?

[sayin]

Is it possible to get partial derivatives wrt 'x', 't' from just discrete data arranged in a matrix with 'x' values in rows and 't' values in columns?

[momchilmm]

You could try using my branch and my API for numerical vjps: PR

Note that the vjp_numeric function takes an optional step argument, which can be defined as the separation between your x-s.