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NAME
     zungqr - generate an M-by-N complex matrix Q with  orthonor-
     mal columns,

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

     INTEGER INFO, K, LDA, LWORK, M, N

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



     #include <sunperf.h>

     void zungqr(int m, int n, int k, doublecomplex *za, int lda,
               doublecomplex *tau, int *info) ;

PURPOSE
     ZUNGQR generates an M-by-N complex matrix Q with orthonormal
     columns,  which  is defined as the first N columns of a pro-
     duct of K elementary reflectors of order M

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

     as returned by ZGEQRF.


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*16 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 ZGEQRF 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*16 array, dimension (K)
               TAU(i) must contain the scalar factor of the  ele-
               mentary reflector H(i), as returned by ZGEQRF.

     WORK      (workspace/output)  COMPLEX*16  array,   dimension
               (LWORK)
               On exit, if INFO = 0, WORK(1) returns the  optimal
               LWORK.

     LWORK     (input) INTEGER
               The  dimension  of  the  array  WORK.   LWORK   >=
               max(1,N).   For optimum performance LWORK >= N*NB,
               where NB is the optimal blocksize.

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

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