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zgbbrd.f(3) LAPACK zgbbrd.f(3)

zgbbrd.f -


subroutine zgbbrd (VECT, M, N, NCC, KL, KU, AB, LDAB, D, E, Q, LDQ, PT, LDPT, C, LDC, WORK, RWORK, INFO)
 
ZGBBRD

ZGBBRD
Purpose:
 ZGBBRD reduces a complex general m-by-n band matrix A to real upper
 bidiagonal form B by a unitary transformation: Q**H * A * P = B.
The routine computes B, and optionally forms Q or P**H, or computes Q**H*C for a given matrix C.
Parameters:
VECT
          VECT is CHARACTER*1
          Specifies whether or not the matrices Q and P**H are to be
          formed.
          = 'N': do not form Q or P**H;
          = 'Q': form Q only;
          = 'P': form P**H only;
          = 'B': form both.
M
          M is INTEGER
          The number of rows of the matrix A.  M >= 0.
N
          N is INTEGER
          The number of columns of the matrix A.  N >= 0.
NCC
          NCC is INTEGER
          The number of columns of the matrix C.  NCC >= 0.
KL
          KL is INTEGER
          The number of subdiagonals of the matrix A. KL >= 0.
KU
          KU is INTEGER
          The number of superdiagonals of the matrix A. KU >= 0.
AB
          AB is COMPLEX*16 array, dimension (LDAB,N)
          On entry, the m-by-n band matrix A, stored in rows 1 to
          KL+KU+1. The j-th column of A is stored in the j-th column of
          the array AB as follows:
          AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl).
          On exit, A is overwritten by values generated during the
          reduction.
LDAB
          LDAB is INTEGER
          The leading dimension of the array A. LDAB >= KL+KU+1.
D
          D is DOUBLE PRECISION array, dimension (min(M,N))
          The diagonal elements of the bidiagonal matrix B.
E
          E is DOUBLE PRECISION array, dimension (min(M,N)-1)
          The superdiagonal elements of the bidiagonal matrix B.
Q
          Q is COMPLEX*16 array, dimension (LDQ,M)
          If VECT = 'Q' or 'B', the m-by-m unitary matrix Q.
          If VECT = 'N' or 'P', the array Q is not referenced.
LDQ
          LDQ is INTEGER
          The leading dimension of the array Q.
          LDQ >= max(1,M) if VECT = 'Q' or 'B'; LDQ >= 1 otherwise.
PT
          PT is COMPLEX*16 array, dimension (LDPT,N)
          If VECT = 'P' or 'B', the n-by-n unitary matrix P'.
          If VECT = 'N' or 'Q', the array PT is not referenced.
LDPT
          LDPT is INTEGER
          The leading dimension of the array PT.
          LDPT >= max(1,N) if VECT = 'P' or 'B'; LDPT >= 1 otherwise.
C
          C is COMPLEX*16 array, dimension (LDC,NCC)
          On entry, an m-by-ncc matrix C.
          On exit, C is overwritten by Q**H*C.
          C is not referenced if NCC = 0.
LDC
          LDC is INTEGER
          The leading dimension of the array C.
          LDC >= max(1,M) if NCC > 0; LDC >= 1 if NCC = 0.
WORK
          WORK is COMPLEX*16 array, dimension (max(M,N))
RWORK
          RWORK is DOUBLE PRECISION array, dimension (max(M,N))
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 193 of file zgbbrd.f.

Generated automatically by Doxygen for LAPACK from the source code.
Sat Nov 16 2013 Version 3.4.2

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