I am trying to create a formula to evaluate another cell formula from the
formula caller cell address.
Supose a have
a b
1 10 30
2 20 40
3 =A1+A2 =udfEvaluate(A3)

the user-defined-formula udfEvaluate should retieve B1+B2=70, i.e., A3 cell
formula evaluated from its perspective = R[-2]C+R[-1]C

P.S. The real formula is huge and does not fit in name-defined.