CXML
        	    
LAPACK version 3.0
zungqr(3)

PURPOSE
  ZUNGQR - generate an M-by-N complex matrix Q with orthonormal columns,

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

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

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

DESCRIPTION
  ZUNGQR 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 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 elementary 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.

	  If LWORK = -1, then a workspace query is assumed; the routine only
	  calculates the optimal size of the WORK array, returns this value
	  as the first entry of the WORK array, and no error message related
	  to LWORK is issued by XERBLA.

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