hi, thanks for your message. I didn't three hours ago, but I found a really good explanation of the indirect least squares method including the rules for multiplication in matrices. Tomorrow I will post the solved problem, good night
[SOLVED] question indirect least squares, turning matrices into a system of equations
Here is the answer to the problem in which I got stuck, which happens to be a part of a wider problem in Econometrics in which students are asked to carry out the indirect least squares method ILS step by step. It is indeed required to know matrix operations, dot product operations before studying this method.