cung2r(3F)

NAME
     CUNG2R - generate an m by n complex matrix Q with orthonormal columns,

SYNOPSIS
     SUBROUTINE CUNG2R( M, N, K, A, LDA, TAU, WORK, INFO )

         INTEGER        INFO, K, LDA, M, N

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

PURPOSE
     CUNG2R generates an m by n complex matrix Q with orthonormal columns,
     which is defined as the first n columns of a product of k elementary
     reflectors of order m

           Q  =  H(1) H(2) . . . H(k)

     as returned by CGEQRF.


ARGUMENTS
     M       (input) INTEGER
             The number of rows of the matrix Q. M >= 0.

     N       (input) INTEGER
             The number of columns of the matrix Q. M >= N >= 0.

     K       (input) INTEGER
             The number of elementary reflectors whose product defines the
             matrix Q. N >= K >= 0.

     A       (input/output) COMPLEX array, dimension (LDA,N)
             On entry, the i-th column must contain the vector which defines
             the elementary reflector H(i), for i = 1,2,...,k, as returned by
             CGEQRF in the first k columns of its array argument A.  On exit,
             the m by n matrix Q.

     LDA     (input) INTEGER
             The first dimension of the array A. LDA >= max(1,M).

     TAU     (input) COMPLEX array, dimension (K)
             TAU(i) must contain the scalar factor of the elementary reflector
             H(i), as returned by CGEQRF.

     WORK    (workspace) COMPLEX array, dimension (N)

     INFO    (output) INTEGER
             = 0: successful exit
             < 0: if INFO = -i, the i-th argument has an illegal value