@article {17729,
	title = {Perturbation analysis for the QR decomposition},
	journal = {SIAM Journal on Matrix Analysis and Applications},
	volume = {18},
	year = {1997},
	month = {1997///},
	pages = {775 - 791},
	author = {Chang,X. C. and Paige,C. C. and Stewart, G.W.}
}
