# QR Decomposition

• May 11th 2010, 08:38 PM
Superfish
QR Decomposition
I have a matrix consisting of two square matrices A & B

$
C = \begin {pmatrix} A \\ B \end{pmatrix}
$

and I want to perform QR decomposition on C, to obtain it's upper triangular factorization.

My question is, is it possible to perform QR decomposition on matrices A & B seperately, and somehow still obtain the upper triangular factorization of C?
• May 11th 2010, 08:40 PM
dwsmith
Quote:

Originally Posted by Superfish
I have a matrix consisting of two square matrices A & B

$
C = \begin {pmatrix} A \\ B \end{pmatrix}
$

and I want to perform QR decomposition on C, to obtain it's upper triangular factorization.

My question is, is it possible to perform QR decomposition on matrices A & B seperately, and somehow still obtain the upper triangular factorization of C?

I may not understand what you mean but R is always upper triangular.
• May 11th 2010, 08:51 PM
Superfish
Quote:

Originally Posted by dwsmith
I may not understand what you mean but R is always upper triangular.

Sorry, i think you misunderstood.

I want to get the R matrix of C by performing QR decomposition on the square A and B matrices seperately.
• May 11th 2010, 09:17 PM
dwsmith
So C is related to A and B via a binomial?
• May 11th 2010, 09:36 PM
Superfish
Quote:

Originally Posted by dwsmith
So C is related to A and B via a binomial?

No, C is just matrix A stacked on top of matrix B. Wasn't sure what the latex command is for square brackets.