LaGenQRFactComplex Class Reference

Represent a QR decomposition. More...

#include <gfqrc.h>

List of all members.

Public Member Functions
	LaGenQRFactComplex ()
	LaGenQRFactComplex (LaGenMatComplex &A)
	LaGenQRFactComplex (LaGenQRFactComplex &QR)
	~LaGenQRFactComplex ()
void	decomposeQR_IP (LaGenMatComplex &A)
LaGenMatComplex &	generateQ_IP ()
void	generateQ (LaGenMatComplex &A) const
void	Mat_Mult (LaGenMatComplex &C, bool hermitian, bool from_left) const

---

Detailed Description

Represent a QR decomposition.

This class calculates the QR factorization of a general m-by-n Matrix given by

for , where is an n-by-n upper triangular matrix and is an m-by-m unitary matrix. If is of full rank n, then is non-singular.

See http://www.netlib.org/lapack/lug/node40.html for more details.

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Constructor & Destructor Documentation

LaGenQRFactComplex::LaGenQRFactComplex

(

)

Null constructor. Use decomposeQR_IP() to actually use this object.

LaGenQRFactComplex::LaGenQRFactComplex

(

LaGenMatComplex &

A

)

Constructor that directly calculates the QR decomposition from the given matrix A, in-place. See decomposeQR_IP() for more about the implications of this.

LaGenQRFactComplex::LaGenQRFactComplex

(

LaGenQRFactComplex &

QR

)

Copy constructor.

LaGenQRFactComplex::~LaGenQRFactComplex

(

)

Default destructor.

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Member Function Documentation

void LaGenQRFactComplex::decomposeQR_IP

(

LaGenMatComplex &

A

)

Calculate the QR decomposition of A.

This is in-place, i.e. it destroys the input matrix A and keeps a reference to its memory around. In other words, you cannot do anything with your input matrix A anymore. You can safely delete any references to A because this object will keep its own references still around.

Internally this uses the lapack routine zgeqrf .

LaGenMatComplex& LaGenQRFactComplex::generateQ_IP

(

)

Generate the matrix Q explicitly. This is in-place, i.e. it destroys the internal QR decomposition but only calculates the matrix Q.

Internally this uses the lapack routine zungqr .

void LaGenQRFactComplex::generateQ

(

LaGenMatComplex &

A

)

const

Generate the matrix Q explicitly. The given matrix A will be overwritten by the matrix Q.

Internally this uses the lapack routine zungqr .

void LaGenQRFactComplex::Mat_Mult	(	LaGenMatComplex &	C,
		bool	hermitian,
		bool	from_left
	)		const

Multiply the matrix C by the matrix Q of the QR decomposition that is represented through this object. This method calculates one out of the following four different calculations:

• 
• 
• or
• 

This does not modify the internal QR decomposition, so this multiplication can be applied repeatedly.

Internally this uses the lapack routine zunmqr .

Parameters:

C	The matrix to be multiplied.
hermitian	If true, then (hermitian, or conjugate transposed) is used. If false, then is used directly.
from_left	If true, then Q or is applied from the left so that C=Q*C . If false, then Q is applied from the right so that C=C*Q .