On oblique projection, rank additivity and the moore-penrose inverse of the sum of two matrices
Jürgen Groβ · Linear and Multilinear Algebra · 1999
The existence of certain oblique projectors is revealed by deriving onto-and along-space of a specific projector, namely the Moore-Penrose inverse of the product of two orthogonal projectors. The results are used to create a formula for the Moore-Penrose in-verse of the sum of two rank additive matrices, and to demonstrate relationships with already known facts.