# zgeqpf.f man page

zgeqpf.f —

## Synopsis

### Functions/Subroutines

subroutine zgeqpf (M, N, A, LDA, JPVT, TAU, WORK, RWORK, INFO)
ZGEQPF

## Function/Subroutine Documentation

### subroutine zgeqpf (integer M, integer N, complex*16, dimension( lda, * ) A, integer LDA, integer, dimension( * ) JPVT, complex*16, dimension( * ) TAU, complex*16, dimension( * ) WORK, double precision, dimension( * ) RWORK, integer INFO)

ZGEQPF

Purpose:

``` This routine is deprecated and has been replaced by routine ZGEQP3.

ZGEQPF computes a QR factorization with column pivoting of a
complex M-by-N matrix A: A*P = Q*R.```
Parameters:

M

```          M is INTEGER
The number of rows of the matrix A. M >= 0.```

N

```          N is INTEGER
The number of columns of the matrix A. N >= 0```

A

```          A is COMPLEX*16 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) elementary reflectors.```

LDA

```          LDA is INTEGER
The leading dimension of the array A. LDA >= max(1,M).```

JPVT

```          JPVT is 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

```          TAU is COMPLEX*16 array, dimension (min(M,N))
The scalar factors of the elementary reflectors.```

WORK

`          WORK is COMPLEX*16 array, dimension (N)`

RWORK

`          RWORK is DOUBLE PRECISION array, dimension (2*N)`

INFO

```          INFO is INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value```
Author:

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Date:

December 2016

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**H

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.
-- April 2011                                                      --
For more details see LAPACK Working Note 176.```

Definition at line 150 of file zgeqpf.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page zgeqpf(3) is an alias of zgeqpf.f(3).

Sat Jun 24 2017 Version 3.7.1 LAPACK