SRC/dptcon.f(3)            Library Functions Manual            SRC/dptcon.f(3)

NAME
       SRC/dptcon.f

SYNOPSIS
   Functions/Subroutines
       subroutine dptcon (n, d, e, anorm, rcond, work, info)
           DPTCON

Function/Subroutine Documentation
   subroutine dptcon (integer n, double precision, dimension( * ) d, double
       precision, dimension( * ) e, double precision anorm, double precision
       rcond, double precision, dimension( * ) work, integer info)
       DPTCON

       Purpose:


           !>
           !> DPTCON 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
           !> DPTTRF.
           !>
           !> 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 DPTTRF.
           !>

           E

           !>          E is DOUBLE PRECISION 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 DPTTRF.
           !>

           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.
           !>

           WORK

           !>          WORK 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, , SIAM J. Sci. Stat. Comput., Vol. 7, No. 1, January 1986.
           !>

       Definition at line 117 of file dptcon.f.

Author
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LAPACK                          Version 3.12.0                 SRC/dptcon.f(3)