Provided by: liblapack-doc_3.3.1-1_all bug

NAME

       LAPACK-3 - computes a QR factorization with column pivoting of the block A(OFFSET+1:M,1:N)

SYNOPSIS

       SUBROUTINE ZLAQP2( M, N, OFFSET, A, LDA, JPVT, TAU, VN1, VN2, WORK )

           INTEGER        LDA, M, N, OFFSET

           INTEGER        JPVT( * )

           DOUBLE         PRECISION VN1( * ), VN2( * )

           COMPLEX*16     A( LDA, * ), TAU( * ), WORK( * )

PURPOSE

       ZLAQP2 computes a QR factorization with column pivoting of the block A(OFFSET+1:M,1:N).
        The block A(1:OFFSET,1:N) is accordingly pivoted, but not factorized.

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.

        OFFSET  (input) INTEGER
                The number of rows of the matrix A that must be pivoted
                but no factorized. OFFSET >= 0.

        A       (input/output) COMPLEX*16 array, dimension (LDA,N)
                On entry, the M-by-N matrix A.
                On exit, the upper triangle of block A(OFFSET+1:M,1:N) is
                the triangular factor obtained; the elements in block
                A(OFFSET+1:M,1:N) below the diagonal, together with the
                array TAU, represent the orthogonal matrix Q as a product of
                elementary reflectors. Block A(1:OFFSET,1:N) has been
                accordingly pivoted, but no factorized.

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

        VN1     (input/output) DOUBLE PRECISION array, dimension (N)
                The vector with the partial column norms.

        VN2     (input/output) DOUBLE PRECISION array, dimension (N)
                The vector with the exact column norms.

        WORK    (workspace) COMPLEX*16 array, dimension (N)

FURTHER DETAILS

        Based on contributions by
          G. Quintana-Orti, Depto. de Informatica, Universidad Jaime I, Spain
          X. Sun, Computer Science Dept., Duke University, USA
        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.

 LAPACK auxiliary routine (version 3.3.1)   April 2011                            ZLAQP2(3lapack)