Mixed dataset calculations

Need to be able to call a user defined function and pass it data from more than 1 dataset. Table lookup with interpolation/extrapolation is very valuable. Need to be able to use values from 1 dataset and lookup/interpolate in another.

For Ex

table 1:

x y ...

0 10

1 10

2 10

3 20

4 20

...

table 2:

xlookup zlookup

0 100

10 200

calculate z in table1 from table1 using lookup data in table 2

x z (calculated)

0 100

1 110

2 120

3 130

4 140

Need to be able to call a function and pass it data from the 2 datasets like

z = lookup(x:1,xlookup:2,zlookup:2,...)

and so I can compute whatever i want and put the result in table 1