The orthogonal projection gives
The first summand has every column in the column space of , and the second has every column in its orthogonal complement. They therefore have zero Frobenius inner product. The Pythagorean identity, together with , gives the stronger exact formula
Consequently
with equality exactly when . Thus solving the linear least-squares problem for each column chooses the best coefficients in the prescribed column space.

Articles by others on the same topic (0)

There are currently no matching articles.