dgbcon (3) - Linux Manuals
NAME
dgbcon.f -
SYNOPSIS
Functions/Subroutines
subroutine dgbcon (NORM, N, KL, KU, AB, LDAB, IPIV, ANORM, RCOND, WORK, IWORK, INFO)
DGBCON
Function/Subroutine Documentation
subroutine dgbcon (characterNORM, integerN, integerKL, integerKU, double precision, dimension( ldab, * )AB, integerLDAB, integer, dimension( * )IPIV, double precisionANORM, double precisionRCOND, double precision, dimension( * )WORK, integer, dimension( * )IWORK, integerINFO)
DGBCON
Purpose:
-
DGBCON estimates the reciprocal of the condition number of a real general band matrix A, in either the 1-norm or the infinity-norm, using the LU factorization computed by DGBTRF. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCOND = 1 / ( norm(A) * norm(inv(A)) ).
Parameters:
-
NORM
NORM is CHARACTER*1 Specifies whether the 1-norm condition number or the infinity-norm condition number is required: = '1' or 'O': 1-norm; = 'I': Infinity-norm.
NN is INTEGER The order of the matrix A. N >= 0.
KLKL is INTEGER The number of subdiagonals within the band of A. KL >= 0.
KUKU is INTEGER The number of superdiagonals within the band of A. KU >= 0.
ABAB is DOUBLE PRECISION array, dimension (LDAB,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.
LDABLDAB is INTEGER The leading dimension of the array AB. LDAB >= 2*KL+KU+1.
IPIVIPIV is INTEGER array, dimension (N) The pivot indices; for 1 <= i <= N, row i of the matrix was interchanged with row IPIV(i).
ANORMANORM is DOUBLE PRECISION If NORM = '1' or 'O', the 1-norm of the original matrix A. If NORM = 'I', the infinity-norm of the original matrix A.
RCONDRCOND is DOUBLE PRECISION The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).
WORKWORK is DOUBLE PRECISION array, dimension (3*N)
IWORKIWORK is INTEGER array, dimension (N)
INFOINFO 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 146 of file dgbcon.f.
Author
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