
dgbbrd.f(3) LAPACK dgbbrd.f(3)
NAME
dgbbrd.f 
SYNOPSIS
Functions/Subroutines
subroutine dgbbrd (VECT, M, N, NCC, KL, KU, AB, LDAB, D, E, Q, LDQ, PT, LDPT, C, LDC,
WORK, INFO)
DGBBRD
Function/Subroutine Documentation
subroutine dgbbrd (characterVECT, integerM, integerN, integerNCC, integerKL, integerKU, double
precision, dimension( ldab, * )AB, integerLDAB, double precision, dimension( * )D, double
precision, dimension( * )E, double precision, dimension( ldq, * )Q, integerLDQ, double
precision, dimension( ldpt, * )PT, integerLDPT, double precision, dimension( ldc, * )C,
integerLDC, double precision, dimension( * )WORK, integerINFO)
DGBBRD
Purpose:
DGBBRD reduces a real general mbyn band matrix A to upper
bidiagonal form B by an orthogonal transformation: Q**T * A * P = B.
The routine computes B, and optionally forms Q or P**T, or computes
Q**T*C for a given matrix C.
Parameters:
VECT
VECT is CHARACTER*1
Specifies whether or not the matrices Q and P**T are to be
formed.
= 'N': do not form Q or P**T;
= 'Q': form Q only;
= 'P': form P**T 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 DOUBLE PRECISION array, dimension (LDAB,N)
On entry, the mbyn band matrix A, stored in rows 1 to
KL+KU+1. The jth column of A is stored in the jth column of
the array AB as follows:
AB(ku+1+ij,j) = A(i,j) for max(1,jku)<=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 DOUBLE PRECISION array, dimension (LDQ,M)
If VECT = 'Q' or 'B', the mbym orthogonal 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 DOUBLE PRECISION array, dimension (LDPT,N)
If VECT = 'P' or 'B', the nbyn orthogonal 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 DOUBLE PRECISION array, dimension (LDC,NCC)
On entry, an mbyncc matrix C.
On exit, C is overwritten by Q**T*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 DOUBLE PRECISION array, dimension (2*max(M,N))
INFO
INFO is INTEGER
= 0: successful exit.
< 0: if INFO = i, the ith 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 187 of file dgbbrd.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 dgbbrd.f(3) 
