SYNOPSIS

Functions/Subroutines

subroutine zunmbr (VECT, SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK, LWORK, INFO)

ZUNMBR

Function/Subroutine Documentation

subroutine zunmbr (characterVECT, characterSIDE, characterTRANS, integerM, integerN, integerK, complex*16, dimension( lda, * )A, integerLDA, complex*16, dimension( * )TAU, complex*16, dimension( ldc, * )C, integerLDC, complex*16, dimension( * )WORK, integerLWORK, integerINFO)

ZUNMBR

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 elementary 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).

Parameters:

VECT

          VECT is CHARACTER*1
          = 'Q': apply Q or Q**H;
          = 'P': apply P or P**H.

SIDE

          SIDE is 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

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

M

          M is INTEGER
          The number of rows of the matrix C. M >= 0.

N

          N is INTEGER
          The number of columns of the matrix C. N >= 0.

K

          K is 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

          A is 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

          LDA is 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

          TAU is 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

          C is 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

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

WORK

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

LWORK

          LWORK is INTEGER
          The dimension of the array WORK.
          If SIDE = 'L', LWORK >= max(1,N);
          if SIDE = 'R', LWORK >= max(1,M);
          if N = 0 or M = 0, LWORK >= 1.
          For optimum performance LWORK >= max(1,N*NB) if SIDE = 'L',
          and LWORK >= max(1,M*NB) if SIDE = 'R', where NB is the
          optimal blocksize. (NB = 0 if M = 0 or N = 0.)

          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

          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 196 of file zunmbr.f.

Author

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