1ZLARZB(1)                LAPACK routine (version 3.1)                ZLARZB(1)
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NAME

6       ZLARZB - a complex block reflector H or its transpose H**H to a complex
7       distributed M-by-N C from the left or the right
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SYNOPSIS

10       SUBROUTINE ZLARZB( SIDE, TRANS, DIRECT, STOREV, M, N, K, L, V, LDV,  T,
11                          LDT, C, LDC, WORK, LDWORK )
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13           CHARACTER      DIRECT, SIDE, STOREV, TRANS
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15           INTEGER        K, L, LDC, LDT, LDV, LDWORK, M, N
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17           COMPLEX*16     C( LDC, * ), T( LDT, * ), V( LDV, * ), WORK( LDWORK,
18                          * )
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PURPOSE

21       ZLARZB applies a complex block reflector H or its transpose H**H  to  a
22       complex distributed M-by-N  C from the left or the right.
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24       Currently, only STOREV = 'R' and DIRECT = 'B' are supported.
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ARGUMENTS

28       SIDE    (input) CHARACTER*1
29               = 'L': apply H or H' from the Left
30               = 'R': apply H or H' from the Right
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32       TRANS   (input) CHARACTER*1
33               = 'N': apply H (No transpose)
34               = 'C': apply H' (Conjugate transpose)
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36       DIRECT  (input) CHARACTER*1
37               Indicates  how H is formed from a product of elementary reflec‐
38               tors = 'F': H = H(1) H(2) . . . H(k)  (Forward,  not  supported
39               yet)
40               = 'B': H = H(k) . . . H(2) H(1) (Backward)
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42       STOREV  (input) CHARACTER*1
43               Indicates  how  the vectors which define the elementary reflec‐
44               tors are stored:
45               = 'C': Columnwise                        (not supported yet)
46               = 'R': Rowwise
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48       M       (input) INTEGER
49               The number of rows of the matrix C.
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51       N       (input) INTEGER
52               The number of columns of the matrix C.
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54       K       (input) INTEGER
55               The order of the matrix T (= the number of  elementary  reflec‐
56               tors whose product defines the block reflector).
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58       L       (input) INTEGER
59               The number of columns of the matrix V containing the meaningful
60               part of the Householder reflectors.  If SIDE = 'L', M >=  L  >=
61               0, if SIDE = 'R', N >= L >= 0.
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63       V       (input) COMPLEX*16 array, dimension (LDV,NV).
64               If STOREV = 'C', NV = K; if STOREV = 'R', NV = L.
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66       LDV     (input) INTEGER
67               The  leading dimension of the array V.  If STOREV = 'C', LDV >=
68               L; if STOREV = 'R', LDV >= K.
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70       T       (input) COMPLEX*16 array, dimension (LDT,K)
71               The triangular K-by-K matrix T in  the  representation  of  the
72               block reflector.
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74       LDT     (input) INTEGER
75               The leading dimension of the array T. LDT >= K.
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77       C       (input/output) COMPLEX*16 array, dimension (LDC,N)
78               On  entry,  the  M-by-N matrix C.  On exit, C is overwritten by
79               H*C or H'*C or C*H or C*H'.
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81       LDC     (input) INTEGER
82               The leading dimension of the array C. LDC >= max(1,M).
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84       WORK    (workspace) COMPLEX*16 array, dimension (LDWORK,K)
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86       LDWORK  (input) INTEGER
87               The leading dimension of the array WORK.  If SIDE = 'L', LDWORK
88               >= max(1,N); if SIDE = 'R', LDWORK >= max(1,M).
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FURTHER DETAILS

91       Based on contributions by
92         A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
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97 LAPACK routine (version 3.1)    November 2006                       ZLARZB(1)
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