naginterfaces.library.blas.dnhousg¶
- naginterfaces.library.blas.dnhousg(alpha, x, tol)[source]¶
dnhousg
generates a real elementary reflection in the NAG (as opposed to LINPACK) style.For full information please refer to the NAG Library document for f06fr
https://support.nag.com/numeric/nl/nagdoc_30.2/flhtml/f06/f06frf.html
- Parameters
- alphafloat
The scalar .
- xfloat, array-like, shape
The -element vector .
- tolfloat
The value .
- Returns
- alphafloat
The scalar .
- xfloat, ndarray, shape
The referenced elements are overwritten by details of the real elementary reflection.
- zetafloat
The scalar .
- Raises
- NagValueError
- (errno )
On entry, error in parameter .
Constraint: .
- Notes
No equivalent traditional C interface for this routine exists in the NAG Library.
dnhousg
generates details of a real elementary reflection (Householder matrix), , such thatwhere is orthogonal, and are real scalars, and is an -element real vector.
is given in the form
where is an -element real vector and is a real scalar.
If is such that
where is the machine precision and is a user-supplied tolerance, then is set to , and can be taken to be the unit matrix. Otherwise .