Translate non-square matrices diagonally

when the matrices have same dimension nXn the calculating is easy.

Here we want to find the overlap area while translate 2 non-square matrices diagonally from corner to corner.

Note: main diagonal is not acceptable in our case we need diagonal translation same below image direction.

[KSSV]

Check this: https://in.mathworks.com/matlabcentral/answers/331983-how-to-get-diagonal-elements-of-non-square-matrix

[Jan]

I do not understand what "transforming [...] diagonally from corner to corner" means here.

[Mohammad Al Nagdawi]

We want to do diagonal translation between the first matrix on the top of the second one and calculate the overlap area in each step.