zgbbrd.f(3)

Usage

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, complex16, dimension( ldab, ) ab, integer ldab, double precision, dimension( * ) d, double precision, dimension( * ) e, complex16, dimension( ldq, ) q, integer ldq, complex16, dimension( ldpt, ) pt, integer ldpt, complex16, dimension( ldc, ) c, integer ldc, complex16, 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.

Releases

4 releases since Debian 7 (Wheezy); the text changed 3 times.

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Arch