Talk:Orthogonal projection

Doesn't the formula become the identity matrix?

$$M(M^\top M)^{-1}M^\top = M M^{-1}{(M^\top)}^{-1}M^\top = E$$

-- Bernhard Bauer

No, because M is not a square matrix, but rather M has (typically many) more rows than columns. Michael Hardy 19:05, 19 Apr 2004 (UTC)