1DORMR2(1)                LAPACK routine (version 3.1)                DORMR2(1)
2
3
4

NAME

6       DORMR2  -  the  general real m by n matrix C with   Q * C if SIDE = 'L'
7       and TRANS = 'N', or   Q'* C if SIDE = 'L' and TRANS = 'T', or   C  *  Q
8       if  SIDE  =  'R' and TRANS = 'N', or   C * Q' if SIDE = 'R' and TRANS =
9       'T',
10

SYNOPSIS

12       SUBROUTINE DORMR2( SIDE, TRANS, M, N, K, A, LDA,  TAU,  C,  LDC,  WORK,
13                          INFO )
14
15           CHARACTER      SIDE, TRANS
16
17           INTEGER        INFO, K, LDA, LDC, M, N
18
19           DOUBLE         PRECISION  A( LDA, * ), C( LDC, * ), TAU( * ), WORK(
20                          * )
21

PURPOSE

23       DORMR2 overwrites the general real m by n matrix C with
24
25       where Q is a real orthogonal matrix defined as the product of k elemen‐
26       tary reflectors
27
28             Q = H(1) H(2) . . . H(k)
29
30       as  returned by DGERQF. Q is of order m if SIDE = 'L' and of order n if
31       SIDE = 'R'.
32
33

ARGUMENTS

35       SIDE    (input) CHARACTER*1
36               = 'L': apply Q or Q' from the Left
37               = 'R': apply Q or Q' from the Right
38
39       TRANS   (input) CHARACTER*1
40               = 'N': apply Q  (No transpose)
41               = 'T': apply Q' (Transpose)
42
43       M       (input) INTEGER
44               The number of rows of the matrix C. M >= 0.
45
46       N       (input) INTEGER
47               The number of columns of the matrix C. N >= 0.
48
49       K       (input) INTEGER
50               The number of elementary reflectors whose product  defines  the
51               matrix Q.  If SIDE = 'L', M >= K >= 0; if SIDE = 'R', N >= K >=
52               0.
53
54       A       (input) DOUBLE PRECISION array, dimension
55               (LDA,M) if SIDE = 'L', (LDA,N) if SIDE = 'R' The i-th row  must
56               contain the vector which defines the elementary reflector H(i),
57               for i = 1,2,...,k, as returned by DGERQF in the last k rows  of
58               its  array  argument  A.   A  is  modified  by  the routine but
59               restored on exit.
60
61       LDA     (input) INTEGER
62               The leading dimension of the array A. LDA >= max(1,K).
63
64       TAU     (input) DOUBLE PRECISION array, dimension (K)
65               TAU(i) must contain the scalar factor of the elementary reflec‐
66               tor H(i), as returned by DGERQF.
67
68       C       (input/output) DOUBLE PRECISION array, dimension (LDC,N)
69               On  entry,  the  m by n matrix C.  On exit, C is overwritten by
70               Q*C or Q'*C or C*Q' or C*Q.
71
72       LDC     (input) INTEGER
73               The leading dimension of the array C. LDC >= max(1,M).
74
75       WORK    (workspace) DOUBLE PRECISION array, dimension
76               (N) if SIDE = 'L', (M) if SIDE = 'R'
77
78       INFO    (output) INTEGER
79               = 0: successful exit
80               < 0: if INFO = -i, the i-th argument had an illegal value
81
82
83
84 LAPACK routine (version 3.1)    November 2006                       DORMR2(1)
Impressum