# cgeqpf.f - Man Page

SRC/DEPRECATED/cgeqpf.f

## Synopsis

### Functions/Subroutines

subroutine **cgeqpf** (m, n, a, lda, jpvt, tau, work, rwork, info)**CGEQPF**

## Function/Subroutine Documentation

### subroutine cgeqpf (integer m, integer n, complex, dimension( lda, * ) a, integer lda, integer, dimension( * ) jpvt, complex, dimension( * ) tau, complex, dimension( * ) work, real, dimension( * ) rwork, integer info)

**CGEQPF**

**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This routine is deprecated and has been replaced by routine CGEQP3.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.

**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 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 array, dimension (min(M,N)) The scalar factors of the elementary reflectors.

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

*RWORK*RWORK is REAL 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

Univ. of Colorado Denver

NAG Ltd.

**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 **147** of file **cgeqpf.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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

Tue Nov 28 2023 12:08:41 Version 3.12.0 LAPACK