zptcon.f - Man Page
SRC/zptcon.f
Synopsis
Functions/Subroutines
subroutine zptcon (n, d, e, anorm, rcond, rwork, info)
ZPTCON
Function/Subroutine Documentation
subroutine zptcon (integer n, double precision, dimension( * ) d, complex*16, dimension( * ) e, double precision anorm, double precision rcond, double precision, dimension( * ) rwork, integer info)
ZPTCON
Purpose:
ZPTCON computes the reciprocal of the condition number (in the 1-norm) of a complex Hermitian positive definite tridiagonal matrix using the factorization A = L*D*L**H or A = U**H*D*U computed by ZPTTRF. Norm(inv(A)) is computed by a direct method, and the reciprocal of the condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
- Parameters
N
N is INTEGER The order of the matrix A. N >= 0.
D
D is DOUBLE PRECISION array, dimension (N) The n diagonal elements of the diagonal matrix D from the factorization of A, as computed by ZPTTRF.
E
E is COMPLEX*16 array, dimension (N-1) The (n-1) off-diagonal elements of the unit bidiagonal factor U or L from the factorization of A, as computed by ZPTTRF.
ANORM
ANORM is DOUBLE PRECISION The 1-norm of the original matrix A.
RCOND
RCOND is DOUBLE PRECISION The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is the 1-norm of inv(A) computed in this routine.
RWORK
RWORK is DOUBLE PRECISION array, dimension (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.
Further Details:
The method used is described in Nicholas J. Higham, 'Efficient Algorithms for Computing the Condition Number of a Tridiagonal Matrix', SIAM J. Sci. Stat. Comput., Vol. 7, No. 1, January 1986.
Definition at line 118 of file zptcon.f.
Author
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Referenced By
The man page zptcon(3) is an alias of zptcon.f(3).
Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK