sla_gbrpvgrw.f - Man Page
SRC/sla_gbrpvgrw.f
Synopsis
Functions/Subroutines
real function sla_gbrpvgrw (n, kl, ku, ncols, ab, ldab, afb, ldafb)
SLA_GBRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a general banded matrix.
Function/Subroutine Documentation
real function sla_gbrpvgrw (integer n, integer kl, integer ku, integer ncols, real, dimension( ldab, * ) ab, integer ldab, real, dimension( ldafb, * ) afb, integer ldafb)
SLA_GBRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a general banded matrix.
Purpose:
SLA_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 REAL 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 REAL array, dimension (LDAFB,N) Details of the LU factorization of the band matrix A, as computed by SGBTRF. 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.
Definition at line 115 of file sla_gbrpvgrw.f.
Author
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Referenced By
The man page sla_gbrpvgrw(3) is an alias of sla_gbrpvgrw.f(3).
Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK