qr decomposition method

i found several method of qr factorization like: 1)Gram-Schmidt process 2)Householder transformation 3)Given's rotation

(1) i want to know that which qr method is used in MATLAB to find out qr decomposition?

(2) how can i get the MATLAB source code for [Q,R]=qr(A) function ?

Answer 1

[Stuart]

According to this website, SuiteSparseQR is used by MATLAB's QR command to compute the QR factorization: http://www.cise.ufl.edu/research/sparse/SPQR/. SuiteSparseQR was developed by Dr. Timothy Davis, and its source code is available from that website. Dr. Davis says the algorithm applies Householder transformations to the nonzero entries of the input matrix.