larf(3) LAPACK larf(3)

larf - larf: apply Householder reflector


subroutine clarf (side, m, n, v, incv, tau, c, ldc, work)
CLARF applies an elementary reflector to a general rectangular matrix. subroutine dlarf (side, m, n, v, incv, tau, c, ldc, work)
DLARF applies an elementary reflector to a general rectangular matrix. subroutine slarf (side, m, n, v, incv, tau, c, ldc, work)
SLARF applies an elementary reflector to a general rectangular matrix. subroutine zlarf (side, m, n, v, incv, tau, c, ldc, work)
ZLARF applies an elementary reflector to a general rectangular matrix.

CLARF applies an elementary reflector to a general rectangular matrix.

Purpose:


CLARF applies a complex elementary reflector H to a complex M-by-N
matrix C, from either the left or the right. H is represented in the
form
H = I - tau * v * v**H
where tau is a complex scalar and v is a complex vector.
If tau = 0, then H is taken to be the unit matrix.
To apply H**H (the conjugate transpose of H), supply conjg(tau) instead
tau.

Parameters

SIDE


SIDE is CHARACTER*1
= 'L': form H * C
= 'R': form C * H

M


M is INTEGER
The number of rows of the matrix C.

N


N is INTEGER
The number of columns of the matrix C.

V


V is COMPLEX array, dimension
(1 + (M-1)*abs(INCV)) if SIDE = 'L'
or (1 + (N-1)*abs(INCV)) if SIDE = 'R'
The vector v in the representation of H. V is not used if
TAU = 0.

INCV


INCV is INTEGER
The increment between elements of v. INCV <> 0.

TAU


TAU is COMPLEX
The value tau in the representation of H.

C


C is COMPLEX array, dimension (LDC,N)
On entry, the M-by-N matrix C.
On exit, C is overwritten by the matrix H * C if SIDE = 'L',
or C * H if SIDE = 'R'.

LDC


LDC is INTEGER
The leading dimension of the array C. LDC >= max(1,M).

WORK


WORK is COMPLEX array, dimension
(N) if SIDE = 'L'
or (M) if SIDE = 'R'

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

DLARF applies an elementary reflector to a general rectangular matrix.

Purpose:


DLARF applies a real elementary reflector H to a real m by n matrix
C, from either the left or the right. H is represented in the form
H = I - tau * v * v**T
where tau is a real scalar and v is a real vector.
If tau = 0, then H is taken to be the unit matrix.

Parameters

SIDE


SIDE is CHARACTER*1
= 'L': form H * C
= 'R': form C * H

M


M is INTEGER
The number of rows of the matrix C.

N


N is INTEGER
The number of columns of the matrix C.

V


V is DOUBLE PRECISION array, dimension
(1 + (M-1)*abs(INCV)) if SIDE = 'L'
or (1 + (N-1)*abs(INCV)) if SIDE = 'R'
The vector v in the representation of H. V is not used if
TAU = 0.

INCV


INCV is INTEGER
The increment between elements of v. INCV <> 0.

TAU


TAU is DOUBLE PRECISION
The value tau in the representation of H.

C


C is DOUBLE PRECISION array, dimension (LDC,N)
On entry, the m by n matrix C.
On exit, C is overwritten by the matrix H * C if SIDE = 'L',
or C * H if SIDE = 'R'.

LDC


LDC is INTEGER
The leading dimension of the array C. LDC >= max(1,M).

WORK


WORK is DOUBLE PRECISION array, dimension
(N) if SIDE = 'L'
or (M) if SIDE = 'R'

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

SLARF applies an elementary reflector to a general rectangular matrix.

Purpose:


SLARF applies a real elementary reflector H to a real m by n matrix
C, from either the left or the right. H is represented in the form
H = I - tau * v * v**T
where tau is a real scalar and v is a real vector.
If tau = 0, then H is taken to be the unit matrix.

Parameters

SIDE


SIDE is CHARACTER*1
= 'L': form H * C
= 'R': form C * H

M


M is INTEGER
The number of rows of the matrix C.

N


N is INTEGER
The number of columns of the matrix C.

V


V is REAL array, dimension
(1 + (M-1)*abs(INCV)) if SIDE = 'L'
or (1 + (N-1)*abs(INCV)) if SIDE = 'R'
The vector v in the representation of H. V is not used if
TAU = 0.

INCV


INCV is INTEGER
The increment between elements of v. INCV <> 0.

TAU


TAU is REAL
The value tau in the representation of H.

C


C is REAL array, dimension (LDC,N)
On entry, the m by n matrix C.
On exit, C is overwritten by the matrix H * C if SIDE = 'L',
or C * H if SIDE = 'R'.

LDC


LDC is INTEGER
The leading dimension of the array C. LDC >= max(1,M).

WORK


WORK is REAL array, dimension
(N) if SIDE = 'L'
or (M) if SIDE = 'R'

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

ZLARF applies an elementary reflector to a general rectangular matrix.

Purpose:


ZLARF applies a complex elementary reflector H to a complex M-by-N
matrix C, from either the left or the right. H is represented in the
form
H = I - tau * v * v**H
where tau is a complex scalar and v is a complex vector.
If tau = 0, then H is taken to be the unit matrix.
To apply H**H, supply conjg(tau) instead
tau.

Parameters

SIDE


SIDE is CHARACTER*1
= 'L': form H * C
= 'R': form C * H

M


M is INTEGER
The number of rows of the matrix C.

N


N is INTEGER
The number of columns of the matrix C.

V


V is COMPLEX*16 array, dimension
(1 + (M-1)*abs(INCV)) if SIDE = 'L'
or (1 + (N-1)*abs(INCV)) if SIDE = 'R'
The vector v in the representation of H. V is not used if
TAU = 0.

INCV


INCV is INTEGER
The increment between elements of v. INCV <> 0.

TAU


TAU is COMPLEX*16
The value tau in the representation of H.

C


C is COMPLEX*16 array, dimension (LDC,N)
On entry, the M-by-N matrix C.
On exit, C is overwritten by the matrix H * C if SIDE = 'L',
or C * H if SIDE = 'R'.

LDC


LDC is INTEGER
The leading dimension of the array C. LDC >= max(1,M).

WORK


WORK is COMPLEX*16 array, dimension
(N) if SIDE = 'L'
or (M) if SIDE = 'R'

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

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