Posted by **sergei** on Wednesday, January 7, 2009 at 10:35am.

What does it mean to have two matrix variables written vertically inside parentheses?

In other words, if A and B are matrices, what does this mean (imagine there is one set of parentheses spanning both rows):

(A)

(B)

I'm trying to understand a least squares problem like this:

(A) * C = (D)

(B) (0)

I understand regular least squares problems with matrices, but the parenthesis notation is confusing me.

Thanks!