


ZUNGR2(3f)         LAPACK routine (version 3.1)        ZUNGR2(3f)


NAME
       ZUNGR2 - an m by n complex matrix Q with orthonormal rows,

SYNOPSIS
       SUBROUTINE ZUNGR2( M, N, K, A, LDA, TAU, WORK, INFO )

           INTEGER        INFO, K, LDA, M, N

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

PURPOSE
       ZUNGR2  generates  an  m  by  n complex matrix Q with orthonormal rows,
       which is defined as the last m  rows  of  a  product  of  k  elementary
       reflectors of order n

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

       as returned by ZGERQF.


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. N >= M.

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

       A       (input/output) COMPLEX*16 array, dimension (LDA,N)
               On entry, the (m-k+i)-th row  must  contain  the  vector  which
               defines  the  elementary  reflector H(i), for i = 1,2,...,k, as
               returned by ZGERQF in the last k rows 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*16 array, dimension (K)
               TAU(i) must contain the scalar factor of the elementary reflec-
               tor H(i), as returned by ZGERQF.

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

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








 LAPACK routine (version 3November 2006                         1


