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RedHat 9 (Linux i386) - man page for zunmbr (redhat section l)

ZUNMBR(l)					)					ZUNMBR(l)

NAME
       ZUNMBR - VECT = 'Q', ZUNMBR overwrites the general complex M-by-N matrix C with SIDE = 'L'
       SIDE = 'R' TRANS = 'N'

SYNOPSIS
       SUBROUTINE ZUNMBR( VECT, SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK, LWORK, INFO )

	   CHARACTER	  SIDE, TRANS, VECT

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

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

PURPOSE
       If VECT = 'Q', ZUNMBR overwrites the general complex M-by-N matrix C with SIDE = 'L'  SIDE
       = 'R' TRANS = 'N': Q * C C * Q TRANS = 'C':	Q**H * C       C * Q**H

       If VECT = 'P', ZUNMBR overwrites the general complex M-by-N matrix C with
		       SIDE = 'L'     SIDE = 'R'
       TRANS = 'N':	 P * C		C * P
       TRANS = 'C':	 P**H * C	C * P**H

       Here  Q	and  P**H  are	the unitary matrices determined by ZGEBRD when reducing a complex
       matrix A to bidiagonal form: A = Q * B * P**H. Q and P**H are defined as products of  ele-
       mentary reflectors H(i) and G(i) respectively.

       Let  nq	=  m  if SIDE = 'L' and nq = n if SIDE = 'R'. Thus nq is the order of the unitary
       matrix Q or P**H that is applied.

       If VECT = 'Q', A is assumed to have been an NQ-by-K matrix: if nq >= k, Q = H(1) H(2) .	.
       . H(k);
       if nq < k, Q = H(1) H(2) . . . H(nq-1).

       If  VECT = 'P', A is assumed to have been a K-by-NQ matrix: if k < nq, P = G(1) G(2) . . .
       G(k);
       if k >= nq, P = G(1) G(2) . . . G(nq-1).

ARGUMENTS
       VECT    (input) CHARACTER*1
	       = 'Q': apply Q or Q**H;
	       = 'P': apply P or P**H.

       SIDE    (input) CHARACTER*1
	       = 'L': apply Q, Q**H, P or P**H from the Left;
	       = 'R': apply Q, Q**H, P or P**H from the Right.

       TRANS   (input) CHARACTER*1
	       = 'N':  No transpose, apply Q or P;
	       = 'C':  Conjugate transpose, apply Q**H or P**H.

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

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

       K       (input) INTEGER
	       If VECT = 'Q', the number of columns in the original matrix reduced by ZGEBRD.  If
	       VECT = 'P', the number of rows in the original matrix reduced by ZGEBRD.  K >= 0.

       A       (input) COMPLEX*16 array, dimension
	       (LDA,min(nq,K))	if  VECT  =  'Q'  (LDA,nq)	  if VECT = 'P' The vectors which
	       define the elementary reflectors H(i)  and  G(i),  whose  products  determine  the
	       matrices Q and P, as returned by ZGEBRD.

       LDA     (input) INTEGER
	       The  leading dimension of the array A.  If VECT = 'Q', LDA >= max(1,nq); if VECT =
	       'P', LDA >= max(1,min(nq,K)).

       TAU     (input) COMPLEX*16 array, dimension (min(nq,K))
	       TAU(i) must contain the scalar factor of the elementary	reflector  H(i)  or  G(i)
	       which determines Q or P, as returned by ZGEBRD in the array argument TAUQ or TAUP.

       C       (input/output) COMPLEX*16 array, dimension (LDC,N)
	       On  entry,  the	M-by-N	matrix	C.  On exit, C is overwritten by Q*C or Q**H*C or
	       C*Q**H or C*Q or P*C or P**H*C or C*P or C*P**H.

       LDC     (input) INTEGER
	       The leading dimension of the array C. LDC >= max(1,M).

       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.  If SIDE = 'L', LWORK >= max(1,N); if SIDE = 'R',
	       LWORK >= max(1,M).  For optimum performance LWORK >= N*NB if SIDE = 'L', and LWORK
	       >= M*NB if SIDE = 'R', 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 had an illegal value

LAPACK version 3.0			   15 June 2000 				ZUNMBR(l)


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