A = Q * R

Q^T * A = R

⋮

G_k,lG_i,j * A = G_k,lG_i,jA

G_k,l * G_i,j * A = G_k,lG_i,jA

G_i,j * A = G_i,jA

A = A

A	=	Q * R
Q^T * A	=	R
	⋮
G_k,lG_i,j * A	=	G_k,lG_i,jA
G_k,l * G_i,j * A	=	G_k,lG_i,jA
G_i,j * A	=	G_i,jA
A	=	A