
NAMEzptcon.f SYNOPSISFunctions/Subroutinessubroutine zptcon (N, D, E, ANORM, RCOND, RWORK, INFO) Function/Subroutine Documentationsubroutine zptcon (integerN, double precision, dimension( * )D, complex*16, dimension( * )E, double precisionANORM, double precisionRCOND, double precision, dimension( * )RWORK, integerINFO)ZPTCON Purpose:ZPTCON computes the reciprocal of the condition number (in the 1norm) 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))). N
Author:
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 (N1) The (n1) offdiagonal elements of the unit bidiagonal factor U or L from the factorization of A, as computed by ZPTTRF.ANORM ANORM is DOUBLE PRECISION The 1norm 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 1norm 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 ith argument had an illegal value Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
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. AuthorGenerated automatically by Doxygen for LAPACK from the source code.
Visit the GSP FreeBSD Man Page Interface. 