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where R 1 is an n×n upper triangular matrix, 0 is an (m − n)×n zero matrix, Q 1 is m×n, Q 2 is m×(m − n), and Q 1 and Q 2 both have orthogonal columns. Golub & Van Loan (1996 , §5.2) call Q 1 R 1 the thin QR factorization of A ; Trefethen and Bau call this the reduced QR factorization . [ 1 ]
The QR algorithm was developed in the late 1950s by John G. F. Francis and by Vera N. Kublanovskaya, working independently. [1] [2] [3] The basic idea is to perform a QR decomposition, writing the matrix as a product of an orthogonal matrix and an upper triangular matrix, multiply the factors in the reverse order, and iterate.
two iterations of the Givens rotation (note that the Givens rotation algorithm used here differs slightly from above) yield an upper triangular matrix in order to compute the QR decomposition. In order to form the desired matrix, zeroing elements (2, 1) and (3, 2) is required; element (2, 1) is zeroed first, using a rotation matrix of:
Also known as: UTV decomposition, ULV decomposition, URV decomposition. Applicable to: m-by-n matrix A. Decomposition: =, where T is a triangular matrix, and U and V are unitary matrices. Comment: Similar to the singular value decomposition and to the Schur decomposition.
The pivot or pivot element is the element of a matrix, or an array, which is selected first by an algorithm (e.g. Gaussian elimination, simplex algorithm, etc.), to do certain calculations. In the case of matrix algorithms, a pivot entry is usually required to be at least distinct from zero, and often distant from it; in this case finding this ...
QR decomposition — orthogonal matrix times triangular matrix RRQR factorization — rank-revealing QR factorization, can be used to compute rank of a matrix; Polar decomposition — unitary matrix times positive-semidefinite Hermitian matrix; Decompositions by similarity: Eigendecomposition — decomposition in terms of eigenvectors and ...
An RRQR factorization or rank-revealing QR factorization is a matrix decomposition algorithm based on the QR factorization which can be used to determine the rank of a matrix. [1] The singular value decomposition can be used to generate an RRQR, but it is not an efficient method to do so. [2] An RRQR implementation is available in MATLAB. [3]
QR decomposition, a decomposition of a matrix QR algorithm, an eigenvalue algorithm to perform QR decomposition; Quadratic reciprocity, a theorem from modular arithmetic; Quasireversibility, a property of some queues; Reaction quotient (Q r), a function of the activities or concentrations of the chemical species involved in a chemical reaction