Functional operators in calculator

Hi all,
Am having a calculator like computation forms which does some arithmatical operations in a grid...say like this creates a column where a user can create his own formula on grid columns..it works fine... but the problem is, the user needs funtional operations like MAX,MIN between two column data's..how this could be acheived.... can anyone please help me???

Ex.

Col1 Col2 Col1+Col2 (User Defined)
12 10 22
10 15 25

Col1 Col2 Min(Col1+Col2)+Col2 ----------> how this could be arrived?
12 10 20

Thanks in Advance

No one is there to help me out.......... :-(

try like
iif(col1<col2,col1,col2)+col2