.TH "SRC/cungbr.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
SRC/cungbr.f
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBcungbr\fP (vect, m, n, k, a, lda, tau, work, lwork, info)"
.br
.RI "\fBCUNGBR\fP "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine cungbr (character vect, integer m, integer n, integer k, complex, dimension( lda, * ) a, integer lda, complex, dimension( * ) tau, complex, dimension( * ) work, integer lwork, integer info)"

.PP
\fBCUNGBR\fP  
.PP
\fBPurpose:\fP
.RS 4

.PP
.nf
!>
!> 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\&.
!> 
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fIVECT\fP 
.PP
.nf
!>          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\&.
!> 
.fi
.PP
.br
\fIM\fP 
.PP
.nf
!>          M is INTEGER
!>          The number of rows of the matrix Q or P**H to be returned\&.
!>          M >= 0\&.
!> 
.fi
.PP
.br
\fIN\fP 
.PP
.nf
!>          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)\&.
!> 
.fi
.PP
.br
\fIK\fP 
.PP
.nf
!>          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\&.
!> 
.fi
.PP
.br
\fIA\fP 
.PP
.nf
!>          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\&.
!> 
.fi
.PP
.br
\fILDA\fP 
.PP
.nf
!>          LDA is INTEGER
!>          The leading dimension of the array A\&. LDA >= M\&.
!> 
.fi
.PP
.br
\fITAU\fP 
.PP
.nf
!>          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\&.
!> 
.fi
.PP
.br
\fIWORK\fP 
.PP
.nf
!>          WORK is COMPLEX array, dimension (MAX(1,LWORK))
!>          On exit, if INFO = 0, WORK(1) returns the optimal LWORK\&.
!> 
.fi
.PP
.br
\fILWORK\fP 
.PP
.nf
!>          LWORK is INTEGER
!>          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\&.
!> 
.fi
.PP
.br
\fIINFO\fP 
.PP
.nf
!>          INFO is INTEGER
!>          = 0:  successful exit
!>          < 0:  if INFO = -i, the i-th argument had an illegal value
!> 
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 

.PP
Univ\&. of California Berkeley 

.PP
Univ\&. of Colorado Denver 

.PP
NAG Ltd\&. 
.RE
.PP

.PP
Definition at line \fB156\fP of file \fBcungbr\&.f\fP\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.