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

6       DLARZ  -  a real elementary reflector H to a real M-by-N matrix C, from
7       either the left or the right
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SYNOPSIS

10       SUBROUTINE DLARZ( SIDE, M, N, L, V, INCV, TAU, C, LDC, WORK )
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12           CHARACTER     SIDE
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14           INTEGER       INCV, L, LDC, M, N
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16           DOUBLE        PRECISION TAU
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18           DOUBLE        PRECISION C( LDC, * ), V( * ), WORK( * )
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PURPOSE

21       DLARZ applies a real elementary reflector H to a real M-by-N matrix  C,
22       from either the left or the right. H is represented in the form
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24             H = I - tau * v * v'
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26       where tau is a real scalar and v is a real vector.
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28       If tau = 0, then H is taken to be the unit matrix.
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31       H is a product of k elementary reflectors as returned by DTZRZF.
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ARGUMENTS

35       SIDE    (input) CHARACTER*1
36               = 'L': form  H * C
37               = 'R': form  C * H
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39       M       (input) INTEGER
40               The number of rows of the matrix C.
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42       N       (input) INTEGER
43               The number of columns of the matrix C.
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45       L       (input) INTEGER
46               The number of entries of the vector V containing the meaningful
47               part of the Householder vectors.  If SIDE = 'L', M >= L  >=  0,
48               if SIDE = 'R', N >= L >= 0.
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50       V       (input) DOUBLE PRECISION array, dimension (1+(L-1)*abs(INCV))
51               The  vector v in the representation of H as returned by DTZRZF.
52               V is not used if TAU = 0.
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54       INCV    (input) INTEGER
55               The increment between elements of v. INCV <> 0.
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57       TAU     (input) DOUBLE PRECISION
58               The value tau in the representation of H.
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60       C       (input/output) DOUBLE PRECISION array, dimension (LDC,N)
61               On entry, the M-by-N matrix C.  On exit, C  is  overwritten  by
62               the matrix H * C if SIDE = 'L', or C * H if SIDE = 'R'.
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64       LDC     (input) INTEGER
65               The leading dimension of the array C. LDC >= max(1,M).
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67       WORK    (workspace) DOUBLE PRECISION array, dimension
68               (N) if SIDE = 'L' or (M) if SIDE = 'R'
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FURTHER DETAILS

71       Based on contributions by
72         A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
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77 LAPACK routine (version 3.1)    November 2006                        DLARZ(1)