naginterfaces.library.lapackeig.dormqr¶
- naginterfaces.library.lapackeig.dormqr(side, trans, a, tau, c)[source]¶
dormqr
multiplies an arbitrary real matrix by the real orthogonal matrix from a factorization computed bydgeqrf()
ordgeqp3()
.For full information please refer to the NAG Library document for f08ag
https://support.nag.com/numeric/nl/nagdoc_30.2/flhtml/f08/f08agf.html
- Parameters
- sidestr, length 1
Indicates how or is to be applied to .
or is applied to from the left.
or is applied to from the right.
- transstr, length 1
Indicates whether or is to be applied to .
is applied to .
is applied to .
- afloat, array-like, shape
Note: the required extent for this argument in dimension 1 is determined as follows: if : ; if : ; otherwise: .
Details of the vectors which define the elementary reflectors, as returned by
dgeqrf()
ordgeqp3()
.- taufloat, array-like, shape
Further details of the elementary reflectors, as returned by
dgeqrf()
ordgeqp3()
.- cfloat, array-like, shape
The matrix .
- Returns
- cfloat, ndarray, shape
is overwritten by or or or as specified by and .
- Raises
- NagValueError
- (errno )
On entry, error in parameter .
Constraint: or .
- (errno )
On entry, error in parameter .
Constraint: or .
- (errno )
On entry, error in parameter .
Constraint: .
- (errno )
On entry, error in parameter .
Constraint: .
- (errno )
On entry, error in parameter .
Constraint: .
- (errno )
On entry, error in parameter .
Constraint: .
- Notes
dormqr
is intended to be used after a call todgeqrf()
ordgeqp3()
which perform a factorization of a real matrix . The orthogonal matrix is represented as a product of elementary reflectors.This function may be used to form one of the matrix products
overwriting the result on (which may be any real rectangular matrix).
A common application of this function is in solving linear least squares problems, as described in the F08 Introduction.
- References
Golub, G H and Van Loan, C F, 1996, Matrix Computations, (3rd Edition), Johns Hopkins University Press, Baltimore