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sptcon.f(3)                         LAPACK                         sptcon.f(3)

NAME
       sptcon.f -

SYNOPSIS
   Functions/Subroutines
       subroutine sptcon (N, D, E, ANORM, RCOND, WORK, INFO)
           SPTCON

Function/Subroutine Documentation
   subroutine sptcon (integerN, real, dimension( * )D, real, dimension( * )E,
       realANORM, realRCOND, real, dimension( * )WORK, integerINFO)
       SPTCON

       Purpose:

            SPTCON computes the reciprocal of the condition number (in the
            1-norm) of a real symmetric positive definite tridiagonal matrix
            using the factorization A = L*D*L**T or A = U**T*D*U computed by
            SPTTRF.

            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 REAL array, dimension (N)
                     The n diagonal elements of the diagonal matrix D from the
                     factorization of A, as computed by SPTTRF.

           E

                     E is REAL 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 SPTTRF.

           ANORM

                     ANORM is REAL
                     The 1-norm of the original matrix A.

           RCOND

                     RCOND is REAL
                     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.

           WORK

                     WORK is REAL 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.

       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.

       Definition at line 119 of file sptcon.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2                   Sat Nov 16 2013                    sptcon.f(3)