Linear interpolation

[#1]

Hi,

I need your help to fix this expression that i am using to get the value of a known point x :

Here is the expression :

Sum({$<[Due Year] ={">=$(=(max([Due Year])-($(V_YearBack))))  <=$(=(max([Due Year]) ))"},

Elapse ={"=$(=(Min({1} Aggr(Min({$<[Due Year] ={">=$(=(max([Due Year])-($(V_YearBack))))  <=$(=(max([Due Year]) ))"},

Elapse ={">=$(=(max(Elapse)))"}>} Elapse),[Due Month],[Due Year]))))"}>}Sales_$(V_Currency))/1000

This expression shows an error but i cannot see where is it ?

My known point x i get it with this expession :

=Min({1} Aggr(Min({$<[Due Year] ={">=$(=(max([Due Year])-($(V_YearBack))))  <=$(=(max([Due Year]) ))"},

Elapse ={">=$(=(max(Elapse)))"}>} Elapse),[Due Month],[Due Year]))

Can you please help to fix it ?

Thanks

[#2]

Hi imen,

Can u please hepl me on interpolation formula

Plesae explain your expr, with all values in that, i mean used column names variables. I am new to this one.

Thanks