CGEQPF(1) LAPACK deprecated driver routine (version 3.2) CGEQPF(1)NAME
CGEQPF - routine i deprecated and has been replaced by routine CGEQP3
SYNOPSIS
SUBROUTINE CGEQPF( M, N, A, LDA, JPVT, TAU, WORK, RWORK, INFO )
INTEGER INFO, LDA, M, N
INTEGER JPVT( * )
REAL RWORK( * )
COMPLEX A( LDA, * ), TAU( * ), WORK( * )
PURPOSE
This routine is deprecated and has been replaced by routine CGEQP3.
CGEQPF computes a QR factorization with column pivoting of a complex M-
by-N matrix A: A*P = Q*R.
ARGUMENTS
M (input) INTEGER
The number of rows of the matrix A. M >= 0.
N (input) INTEGER
The number of columns of the matrix A. N >= 0
A (input/output) COMPLEX array, dimension (LDA,N)
On entry, the M-by-N matrix A. On exit, the upper triangle of
the array contains the min(M,N)-by-N upper triangular matrix R;
the elements below the diagonal, together with the array TAU,
represent the unitary matrix Q as a product of min(m,n) elemenā
tary reflectors.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,M).
JPVT (input/output) INTEGER array, dimension (N)
On entry, if JPVT(i) .ne. 0, the i-th column of A is permuted
to the front of A*P (a leading column); if JPVT(i) = 0, the i-
th column of A is a free column. On exit, if JPVT(i) = k, then
the i-th column of A*P was the k-th column of A.
TAU (output) COMPLEX array, dimension (min(M,N))
The scalar factors of the elementary reflectors.
WORK (workspace) COMPLEX array, dimension (N)
RWORK (workspace) REAL array, dimension (2*N)
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
FURTHER DETAILS
The matrix Q is represented as a product of elementary reflectors
Q = H(1)H(2) . . . H(n)
Each H(i) has the form
H = I - tau * v * v'
where tau is a complex scalar, and v is a complex vector with v(1:i-1)
= 0 and v(i) = 1; v(i+1:m) is stored on exit in A(i+1:m,i). The matrix
P is represented in jpvt as follows: If
jpvt(j) = i
then the jth column of P is the ith canonical unit vector. Partial
column norm updating strategy modified by
Z. Drmac and Z. Bujanovic, Dept. of Mathematics,
University of Zagreb, Croatia.
June 2006.
For more details see LAPACK Working Note 176.
LAPACK deprecated driver routineNovembern2008) CGEQPF(1)