DLARFB(3)

NAME
DLARFB - a real block reflector H or its transpose H' to a real m by n matrix C, from either the left or the right

SYNOPSIS

SUBROUTINE DLARFB(
    SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV, T, LDT, C, LDC, WORK, LDWORK )

CHARACTER
    DIRECT, SIDE, STOREV, TRANS

INTEGER
    K, LDC, LDT, LDV, LDWORK, M, N

DOUBLE
    PRECISION C( LDC, * ), T( LDT, * ), V( LDV, * ), WORK( LDWORK, * )

PURPOSE
DLARFB applies a real block reflector H or its transpose H' to a real m by n matrix C, from either the left or the right.

ARGUMENTS

SIDE    (input) CHARACTER*1
    = 'L': apply H or H' from the Left
    = 'R': apply H or H' from the Right

TRANS   (input) CHARACTER*1
    = 'N': apply H (No transpose)
    = 'T': apply H' (Transpose)

DIRECT  (input) CHARACTER*1
    Indicates how H is formed from a product of elementary reflectors = 'F': H = H(1) H(2) . . . H(k) (Forward)
    = 'B': H = H(k) . . . H(2) H(1) (Backward)

STOREV  (input) CHARACTER*1
    Indicates how the vectors which define the elementary reflectors are stored:
    = 'C': Columnwise
    = 'R': Rowwise

M       (input) INTEGER
    The number of rows of the matrix C.

N       (input) INTEGER
    The number of columns of the matrix C.

K       (input) INTEGER
    The order of the matrix T (= the number of elementary reflectors whose product defines the block reflector).

V       (input) DOUBLE PRECISION array, dimension
    (LDV,K) if STOREV = 'C' (LDV,M) if STOREV = 'R' and SIDE = 'L' (LDV,N) if STOREV = 'R' and SIDE = 'R' The matrix V. See further details.

LDV     (input) INTEGER
    The leading dimension of the array V. If STOREV = 'C' and SIDE = 'L', LDV >= max(1,M); if STOREV = 'C' and SIDE = 'R', LDV >= max(1,N); if STOREV = 'R', LDV >= K.

T       (input) DOUBLE PRECISION array, dimension (LDT,K)
    The triangular k by k matrix T in the representation of the block reflector.

LDT     (input) INTEGER
    The leading dimension of the array T. LDT >= K.

C       (input/output) DOUBLE PRECISION array, dimension (LDC,N)
    On entry, the m by n matrix C. On exit, C is overwritten by H*C or H'*C or C*H or C*H'.

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

WORK    (workspace) DOUBLE PRECISION array, dimension (LDWORK,K)

LDWORK  (input) INTEGER
    The leading dimension of the array WORK. If SIDE = 'L', LDWORK >= max(1,N); if SIDE = 'R', LDWORK >= max(1,M).