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.

   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.

   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.

   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.

Author

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