I think I already know the answer but I need to ask just on case

If one defines a matrix (3x3) (CTRL+SHIFT+ENTER) is there a way of calling this matrix with an argument?

See attached for example

The only way I can think of is to create a simple function which takes theta as an argument and return a "matrix" so that I could have in any cell (using CTRL+SHIFT+ENTER)

=MMULT(myrotationmatrix(theta),A1:A3)

where A1:A3 is the input vector

Thanks

Regards

JXB