1CGEQPF(1)       LAPACK deprecated driver routine (version 3.2)       CGEQPF(1)
2
3
4

NAME

6       CGEQPF - routine i deprecated and has been replaced by routine CGEQP3
7

SYNOPSIS

9       SUBROUTINE CGEQPF( M, N, A, LDA, JPVT, TAU, WORK, RWORK, INFO )
10
11           INTEGER        INFO, LDA, M, N
12
13           INTEGER        JPVT( * )
14
15           REAL           RWORK( * )
16
17           COMPLEX        A( LDA, * ), TAU( * ), WORK( * )
18

PURPOSE

20       This  routine  is  deprecated  and has been replaced by routine CGEQP3.
21       CGEQPF computes a QR factorization with column pivoting of a complex M-
22       by-N matrix A: A*P = Q*R.
23

ARGUMENTS

25       M       (input) INTEGER
26               The number of rows of the matrix A. M >= 0.
27
28       N       (input) INTEGER
29               The number of columns of the matrix A. N >= 0
30
31       A       (input/output) COMPLEX array, dimension (LDA,N)
32               On  entry, the M-by-N matrix A.  On exit, the upper triangle of
33               the array contains the min(M,N)-by-N upper triangular matrix R;
34               the  elements  below the diagonal, together with the array TAU,
35               represent the unitary matrix Q as a product of min(m,n) elemen‐
36               tary reflectors.
37
38       LDA     (input) INTEGER
39               The leading dimension of the array A. LDA >= max(1,M).
40
41       JPVT    (input/output) INTEGER array, dimension (N)
42               On  entry,  if JPVT(i) .ne. 0, the i-th column of A is permuted
43               to the front of A*P (a leading column); if JPVT(i) = 0, the  i-
44               th column of A is a free column.  On exit, if JPVT(i) = k, then
45               the i-th column of A*P was the k-th column of A.
46
47       TAU     (output) COMPLEX array, dimension (min(M,N))
48               The scalar factors of the elementary reflectors.
49
50       WORK    (workspace) COMPLEX array, dimension (N)
51
52       RWORK   (workspace) REAL array, dimension (2*N)
53
54       INFO    (output) INTEGER
55               = 0:  successful exit
56               < 0:  if INFO = -i, the i-th argument had an illegal value
57

FURTHER DETAILS

59       The matrix Q is represented as a product of elementary reflectors
60          Q = H(1) H(2) . . . H(n)
61       Each H(i) has the form
62          H = I - tau * v * v'
63       where tau is a complex scalar, and v is a complex vector with  v(1:i-1)
64       = 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i).  The matrix
65       P is represented in jpvt as follows: If
66          jpvt(j) = i
67       then the jth column of P is the ith  canonical  unit  vector.   Partial
68       column norm updating strategy modified by
69         Z. Drmac and Z. Bujanovic, Dept. of Mathematics,
70         University of Zagreb, Croatia.
71         June 2006.
72       For more details see LAPACK Working Note 176.
73
74
75
76 LAPACK deprecated driver routineN(ovveermsbieorn230.028)                      CGEQPF(1)
Impressum