[Paraview] Array look-ups in Calculator filter

[Chad Glendenin]

Is there a way to have the calculator filter perform an operation where 
the generation of each point in the output array requires information 
from more than one point in the input array? I'm looking to do something 
like this:

* let A = scalar value at input point (x, y, z)
* let B = scalar value at input point (x, y, z+e)
* filter's output at point (x,y,z) = A-B

Is that possible with the calculator (or with some other existing filter)?

Thanks.

ccg