sgbbrd.f man page

sgbbrd.f —

Synopsis

Functions/Subroutines

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

Function/Subroutine Documentation

subroutine sgbbrd (characterVECT, integerM, integerN, integerNCC, integerKL, integerKU, real, dimension( ldab, * )AB, integerLDAB, real, dimension( * )D, real, dimension( * )E, real, dimension( ldq, * )Q, integerLDQ, real, dimension( ldpt, * )PT, integerLDPT, real, dimension( ldc, * )C, integerLDC, real, dimension( * )WORK, integerINFO)

SGBBRD

Purpose:

SGBBRD reduces a real general m-by-n 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 REAL 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 REAL array, dimension (min(M,N))
The diagonal elements of the bidiagonal matrix B.

E

E is REAL array, dimension (min(M,N)-1)
The superdiagonal elements of the bidiagonal matrix B.

Q

Q is REAL array, dimension (LDQ,M)
If VECT = 'Q' or 'B', the m-by-m 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 REAL array, dimension (LDPT,N)
If VECT = 'P' or 'B', the n-by-n 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 REAL array, dimension (LDC,NCC)
On entry, an m-by-ncc 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 REAL array, dimension (2*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 187 of file sgbbrd.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

sgbbrd(3) is an alias of sgbbrd.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK