1DLARZ(1)                 LAPACK routine (version 3.2)                 DLARZ(1)
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NAME

6       DLARZ  -  applies a real elementary reflector H to a real M-by-N matrix
7       C, from 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
23             H = I - tau * v * v'
24       where tau is a real scalar and v is a real vector.
25       If tau = 0, then H is taken to be the unit matrix.
26       H is a product of k elementary reflectors as returned by DTZRZF.
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ARGUMENTS

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

65       Based on contributions by
66         A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
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70 LAPACK routine (version 3.2)    November 2008                        DLARZ(1)
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