[Paraview] Calculator filter

[Liam Healy]

I am trying to compute a quantity based on two 3-vectors as input. All
six components are in six columns of one (csv) file, so I read that in
and create two Table to Points filters. I would like to bring up the
calculator to compute the magnitudes of each vector, but if I
highlight the two filters I cannot select the Calculator tool, it is
greyed out. How do I do computations on two (or more) inputs?

Thanks,
Liam