SRC/zgbbrd.f(3)

NAME
SRC/zgbbrd.f

SYNOPSIS

  Functions/Subroutines
subroutine zgbbrd (vect, m, n, ncc, kl, ku, ab, ldab, d, e, q, ldq, pt, ldpt, c, ldc, work, rwork, info)
ZGBBRD

Function/Subroutine Documentation

  subroutine zgbbrd (character vect, integer m, integer n, integer ncc, integer kl, integer ku, complex*16, dimension( ldab, * ) ab, integer ldab, double precision, dimension( * ) d, double precision, dimension( * ) e, complex*16, dimension( ldq, * ) q, integer ldq, complex*16, dimension( ldpt, * ) pt, integer ldpt, complex*16, dimension( ldc, * ) c, integer ldc, complex*16, dimension( * ) work, double precision, dimension( * ) rwork, integer info)

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.

Definition at line 191 of file zgbbrd.f.

Author

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