im not sure this question is supposed to be under what topic but here is my question:
given taht A is a sq matrix
(A^t)A = I iff (Ai)(Ai) =1 for all i.
also, what does it mean by an orthonormal basis being a basis consisting of mutually orthogonal unit vectors? does it mean that if A is a sq matrix, then the column vectors in A are orthogonal to each other?