
dla_gbrcond.f(3) LAPACK dla_gbrcond.f(3)
NAME
dla_gbrcond.f 
SYNOPSIS
Functions/Subroutines
DOUBLE PRECISION function dla_gbrcond (TRANS, N, KL, KU, AB, LDAB, AFB, LDAFB, IPIV,
CMODE, C, INFO, WORK, IWORK)
DLA_GBRCOND estimates the Skeel condition number for a general banded matrix.
Function/Subroutine Documentation
DOUBLE PRECISION function dla_gbrcond (characterTRANS, integerN, integerKL, integerKU, double
precision, dimension( ldab, * )AB, integerLDAB, double precision, dimension( ldafb, *
)AFB, integerLDAFB, integer, dimension( * )IPIV, integerCMODE, double precision,
dimension( * )C, integerINFO, double precision, dimension( * )WORK, integer, dimension( *
)IWORK)
DLA_GBRCOND estimates the Skeel condition number for a general banded matrix.
Purpose:
DLA_GBRCOND Estimates the Skeel condition number of op(A) * op2(C)
where op2 is determined by CMODE as follows
CMODE = 1 op2(C) = C
CMODE = 0 op2(C) = I
CMODE = 1 op2(C) = inv(C)
The Skeel condition number cond(A) = norminf( inv(A)A )
is computed by computing scaling factors R such that
diag(R)*A*op2(C) is row equilibrated and computing the standard
infinitynorm condition number.
Parameters:
TRANS
TRANS is CHARACTER*1
Specifies the form of the system of equations:
= 'N': A * X = B (No transpose)
= 'T': A**T * X = B (Transpose)
= 'C': A**H * X = B (Conjugate Transpose = Transpose)
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.
AB
AB is DOUBLE PRECISION array, dimension (LDAB,N)
On entry, the matrix A in band storage, 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(N,j+kl)
LDAB
LDAB is INTEGER
The leading dimension of the array AB. LDAB >= KL+KU+1.
AFB
AFB is DOUBLE PRECISION array, dimension (LDAFB,N)
Details of the LU factorization of the band matrix A, as
computed by DGBTRF. 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.
IPIV
IPIV is INTEGER array, dimension (N)
The pivot indices from the factorization A = P*L*U
as computed by DGBTRF; row i of the matrix was interchanged
with row IPIV(i).
CMODE
CMODE is INTEGER
Determines op2(C) in the formula op(A) * op2(C) as follows:
CMODE = 1 op2(C) = C
CMODE = 0 op2(C) = I
CMODE = 1 op2(C) = inv(C)
C
C is DOUBLE PRECISION array, dimension (N)
The vector C in the formula op(A) * op2(C).
INFO
INFO is INTEGER
= 0: Successful exit.
i > 0: The ith argument is invalid.
WORK
WORK is DOUBLE PRECISION array, dimension (5*N).
Workspace.
IWORK
IWORK is INTEGER array, dimension (N).
Workspace.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 169 of file dla_gbrcond.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 dla_gbrcond.f(3) 
