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slarfb

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NAME
SLARFB - apply 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 SLARFB( 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

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

PURPOSE
SLARFB 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 elemen-
tary 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 elemen-
tary 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 elemen-
tary reflectors whose product defines the block
reflector).

V       (input) REAL 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) REAL 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) REAL 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) REAL 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).
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