cgeqpf (l)  Linux Man Pages
cgeqpf: routine i deprecated and has been replaced by routine CGEQP3
NAME
CGEQPF  routine i deprecated and has been replaced by routine CGEQP3SYNOPSIS
 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This routine is deprecated and has been replaced by routine CGEQP3.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 MbyN 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 MbyN matrix A. On exit, the upper triangle of the array contains the min(M,N)byN 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) elementary 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 ith column of A is permuted to the front of A*P (a leading column); if JPVT(i) = 0, the ith column of A is a free column. On exit, if JPVT(i) = k, then the ith column of A*P was the kth 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 ith argument had an illegal value
FURTHER DETAILS
The matrix Q is represented as a product of elementary reflectorsQ
Each H(i) has the form
H
where tau is a complex scalar, and v is a complex vector with v(1:i1) = 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)
then the jth column of P is the ith canonical unit vector. Partial column norm updating strategy modified by
For more details see LAPACK Working Note 176.