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larfy(3) LAPACK larfy(3)

larfy - larfy: apply Householder reflector symmetrically (2-sided)


subroutine clarfy (uplo, n, v, incv, tau, c, ldc, work)
CLARFY subroutine dlarfy (uplo, n, v, incv, tau, c, ldc, work)
DLARFY subroutine slarfy (uplo, n, v, incv, tau, c, ldc, work)
SLARFY subroutine zlarfy (uplo, n, v, incv, tau, c, ldc, work)
ZLARFY

CLARFY

Purpose:


CLARFY applies an elementary reflector, or Householder matrix, H,
to an n x n Hermitian matrix C, from both the left and the right.
H is represented in the form
H = I - tau * v * v'
where tau is a scalar and v is a vector.
If tau is zero, then H is taken to be the unit matrix.

Parameters

UPLO


UPLO is CHARACTER*1
Specifies whether the upper or lower triangular part of the
Hermitian matrix C is stored.
= 'U': Upper triangle
= 'L': Lower triangle

N


N is INTEGER
The number of rows and columns of the matrix C. N >= 0.

V


V is COMPLEX array, dimension
(1 + (N-1)*abs(INCV))
The vector v as described above.

INCV


INCV is INTEGER
The increment between successive elements of v. INCV must
not be zero.

TAU


TAU is COMPLEX
The value tau as described above.

C


C is COMPLEX array, dimension (LDC, N)
On entry, the matrix C.
On exit, C is overwritten by H * C * H'.

LDC


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

WORK


WORK is COMPLEX array, dimension (N)

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 107 of file clarfy.f.

DLARFY

Purpose:


DLARFY applies an elementary reflector, or Householder matrix, H,
to an n x n symmetric matrix C, from both the left and the right.
H is represented in the form
H = I - tau * v * v'
where tau is a scalar and v is a vector.
If tau is zero, then H is taken to be the unit matrix.

Parameters

UPLO


UPLO is CHARACTER*1
Specifies whether the upper or lower triangular part of the
symmetric matrix C is stored.
= 'U': Upper triangle
= 'L': Lower triangle

N


N is INTEGER
The number of rows and columns of the matrix C. N >= 0.

V


V is DOUBLE PRECISION array, dimension
(1 + (N-1)*abs(INCV))
The vector v as described above.

INCV


INCV is INTEGER
The increment between successive elements of v. INCV must
not be zero.

TAU


TAU is DOUBLE PRECISION
The value tau as described above.

C


C is DOUBLE PRECISION array, dimension (LDC, N)
On entry, the matrix C.
On exit, C is overwritten by H * C * H'.

LDC


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

WORK


WORK is DOUBLE PRECISION array, dimension (N)

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 107 of file dlarfy.f.

SLARFY

Purpose:


SLARFY applies an elementary reflector, or Householder matrix, H,
to an n x n symmetric matrix C, from both the left and the right.
H is represented in the form
H = I - tau * v * v'
where tau is a scalar and v is a vector.
If tau is zero, then H is taken to be the unit matrix.

Parameters

UPLO


UPLO is CHARACTER*1
Specifies whether the upper or lower triangular part of the
symmetric matrix C is stored.
= 'U': Upper triangle
= 'L': Lower triangle

N


N is INTEGER
The number of rows and columns of the matrix C. N >= 0.

V


V is REAL array, dimension
(1 + (N-1)*abs(INCV))
The vector v as described above.

INCV


INCV is INTEGER
The increment between successive elements of v. INCV must
not be zero.

TAU


TAU is REAL
The value tau as described above.

C


C is REAL array, dimension (LDC, N)
On entry, the matrix C.
On exit, C is overwritten by H * C * H'.

LDC


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

WORK


WORK is REAL array, dimension (N)

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 107 of file slarfy.f.

ZLARFY

Purpose:


ZLARFY applies an elementary reflector, or Householder matrix, H,
to an n x n Hermitian matrix C, from both the left and the right.
H is represented in the form
H = I - tau * v * v'
where tau is a scalar and v is a vector.
If tau is zero, then H is taken to be the unit matrix.

Parameters

UPLO


UPLO is CHARACTER*1
Specifies whether the upper or lower triangular part of the
Hermitian matrix C is stored.
= 'U': Upper triangle
= 'L': Lower triangle

N


N is INTEGER
The number of rows and columns of the matrix C. N >= 0.

V


V is COMPLEX*16 array, dimension
(1 + (N-1)*abs(INCV))
The vector v as described above.

INCV


INCV is INTEGER
The increment between successive elements of v. INCV must
not be zero.

TAU


TAU is COMPLEX*16
The value tau as described above.

C


C is COMPLEX*16 array, dimension (LDC, N)
On entry, the matrix C.
On exit, C is overwritten by H * C * H'.

LDC


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

WORK


WORK is COMPLEX*16 array, dimension (N)

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 107 of file zlarfy.f.

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