Hi,
You can use Validate Event for the same (et_Validate).
It depends on how do you want to do it:
1. If you want to loop through each row in the matrix:
for (int i=1; i<= oMatrix.RowCount;i++)
{
// Write your logic here.
}
2. If you want to check it as soon as user enters the value and leave that field:
int Row = pVal.Row;
Get the value of that particular cell using Row variable and write your logic.
Hope it helps.
Kind regards,
ANKIT CHAUHAN
SAP Business One Global Support