CUNGBR man page on Oracle

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cungbr.f(3)			    LAPACK			   cungbr.f(3)

       cungbr.f -

       subroutine cungbr (VECT, M, N, K, A, LDA, TAU, WORK, LWORK, INFO)

Function/Subroutine Documentation
   subroutine cungbr (characterVECT, integerM, integerN, integerK, complex,
       dimension( lda, * )A, integerLDA, complex, dimension( * )TAU, complex,
       dimension( * )WORK, integerLWORK, integerINFO)


	    CUNGBR generates one of the complex unitary matrices Q or P**H
	    determined by CGEBRD when reducing a complex matrix A to bidiagonal
	    form: A = Q * B * P**H.  Q and P**H are defined as products of
	    elementary reflectors H(i) or G(i) respectively.

	    If VECT = 'Q', A is assumed to have been an M-by-K matrix, and Q
	    is of order M:
	    if m >= k, Q = H(1) H(2) . . . H(k) and CUNGBR returns the first n
	    columns of Q, where m >= n >= k;
	    if m < k, Q = H(1) H(2) . . . H(m-1) and CUNGBR returns Q as an
	    M-by-M matrix.

	    If VECT = 'P', A is assumed to have been a K-by-N matrix, and P**H
	    is of order N:
	    if k < n, P**H = G(k) . . . G(2) G(1) and CUNGBR returns the first m
	    rows of P**H, where n >= m >= k;
	    if k >= n, P**H = G(n-1) . . . G(2) G(1) and CUNGBR returns P**H as
	    an N-by-N matrix.


		     VECT is CHARACTER*1
		     Specifies whether the matrix Q or the matrix P**H is
		     required, as defined in the transformation applied by CGEBRD:
		     = 'Q':  generate Q;
		     = 'P':  generate P**H.


		     M is INTEGER
		     The number of rows of the matrix Q or P**H to be returned.
		     M >= 0.


		     N is INTEGER
		     The number of columns of the matrix Q or P**H to be returned.
		     N >= 0.
		     If VECT = 'Q', M >= N >= min(M,K);
		     if VECT = 'P', N >= M >= min(N,K).


		     K is INTEGER
		     If VECT = 'Q', the number of columns in the original M-by-K
		     matrix reduced by CGEBRD.
		     If VECT = 'P', the number of rows in the original K-by-N
		     matrix reduced by CGEBRD.
		     K >= 0.


		     A is COMPLEX array, dimension (LDA,N)
		     On entry, the vectors which define the elementary reflectors,
		     as returned by CGEBRD.
		     On exit, the M-by-N matrix Q or P**H.


		     LDA is INTEGER
		     The leading dimension of the array A. LDA >= M.


		     TAU is COMPLEX array, dimension
					   (min(M,K)) if VECT = 'Q'
					   (min(N,K)) if VECT = 'P'
		     TAU(i) must contain the scalar factor of the elementary
		     reflector H(i) or G(i), which determines Q or P**H, as
		     returned by CGEBRD in its array argument TAUQ or TAUP.


		     WORK is COMPLEX array, dimension (MAX(1,LWORK))
		     On exit, if INFO = 0, WORK(1) returns the optimal LWORK.


		     The dimension of the array WORK. LWORK >= max(1,min(M,N)).
		     For optimum performance LWORK >= min(M,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 is INTEGER
		     = 0:  successful exit
		     < 0:  if INFO = -i, the i-th argument had an illegal value

	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

	   April 2012

       Definition at line 158 of file cungbr.f.

       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2			Tue Sep 25 2012			   cungbr.f(3)

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