larf(3)

NAME
larf - larf: apply Householder reflector

SYNOPSIS

  Functions
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.

Detailed Description

Function Documentation

  subroutine clarf (character side, integer m, integer n, complex, dimension( * ) v, integer incv, complex tau, complex, dimension( ldc, * ) c, integer ldc, complex, dimension( * ) work)

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.

Definition at line 127 of file clarf.f.

  subroutine dlarf (character side, integer m, integer n, double precision, dimension( * ) v, integer incv, double precision tau, double precision, dimension( ldc, * ) c, integer ldc, double precision, dimension( * ) work)

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.

Definition at line 123 of file dlarf.f.

  subroutine slarf (character side, integer m, integer n, real, dimension( * ) v, integer incv, real tau, real, dimension( ldc, * ) c, integer ldc, real, dimension( * ) work)

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.

Definition at line 123 of file slarf.f.

  subroutine zlarf (character side, integer m, integer n, complex*16, dimension( * ) v, integer incv, complex*16 tau, complex*16, dimension( ldc, * ) c, integer ldc, complex*16, dimension( * ) work)

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.

Definition at line 127 of file zlarf.f.

Author

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