sgeqpf (l)  Linux Man Pages
sgeqpf: routine i deprecated and has been replaced by routine SGEQP3
NAME
SGEQPF  routine i deprecated and has been replaced by routine SGEQP3SYNOPSIS
 SUBROUTINE SGEQPF(
 M, N, A, LDA, JPVT, TAU, WORK, INFO )
 INTEGER INFO, LDA, M, N
 INTEGER JPVT( * )
 REAL A( LDA, * ), TAU( * ), WORK( * )
PURPOSE
This routine is deprecated and has been replaced by routine SGEQP3. SGEQPF computes a QR factorization with column pivoting of a real 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) REAL 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 orthogonal 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) REAL array, dimension (min(M,N))
 The scalar factors of the elementary reflectors.
 WORK (workspace) REAL array, dimension (3*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 real scalar, and v is a real 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.