zla_gbrpvgrw.f man page

zla_gbrpvgrw.f —

Synopsis

Functions/Subroutines

DOUBLE PRECISION function zla_gbrpvgrw (N, KL, KU, NCOLS, AB, LDAB, AFB, LDAFB)
ZLA_GBRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a general banded matrix.

Function/Subroutine Documentation

DOUBLE PRECISION function zla_gbrpvgrw (integerN, integerKL, integerKU, integerNCOLS, complex*16, dimension( ldab, * )AB, integerLDAB, complex*16, dimension( ldafb, * )AFB, integerLDAFB)

ZLA_GBRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a general banded matrix.

Purpose:

ZLA_GBRPVGRW computes the reciprocal pivot growth factor
norm(A)/norm(U). The "max absolute element" norm is used. If this is
much less than 1, the stability of the LU factorization of the
(equilibrated) matrix A could be poor. This also means that the
solution X, estimated condition numbers, and error bounds could be
unreliable.

Parameters:

N

     N is INTEGER
The number of linear equations, i.e., the order of the
matrix A.  N >= 0.

KL

     KL is INTEGER
The number of subdiagonals within the band of A.  KL >= 0.

KU

     KU is INTEGER
The number of superdiagonals within the band of A.  KU >= 0.

NCOLS

     NCOLS is INTEGER
The number of columns of the matrix A.  NCOLS >= 0.

AB

     AB is COMPLEX*16 array, dimension (LDAB,N)
On entry, the matrix A in band storage, 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(N,j+kl)

LDAB

     LDAB is INTEGER
The leading dimension of the array AB.  LDAB >= KL+KU+1.

AFB

     AFB is COMPLEX*16 array, dimension (LDAFB,N)
Details of the LU factorization of the band matrix A, as
computed by ZGBTRF.  U is stored as an upper triangular
band matrix with KL+KU superdiagonals in rows 1 to KL+KU+1,
and the multipliers used during the factorization are stored
in rows KL+KU+2 to 2*KL+KU+1.

LDAFB

     LDAFB is INTEGER
The leading dimension of the array AFB.  LDAFB >= 2*KL+KU+1.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 117 of file zla_gbrpvgrw.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

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

Sat Nov 16 2013 Version 3.4.2 LAPACK