CPTCON(3)      LAPACK routine of NEC Numeric Library Collection      CPTCON(3)



NAME
       CPTCON

SYNOPSIS
       SUBROUTINE CPTCON (N, D, E, ANORM, RCOND, RWORK, INFO)



PURPOSE
            CPTCON 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
            CPTTRF.

            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))).




ARGUMENTS
           N         (input)
                     N is INTEGER
                     The order of the matrix A.  N >= 0.

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

           E         (input)
                     E is COMPLEX 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 CPTTRF.

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

           RCOND     (output)
                     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.

           RWORK     (output)
                     RWORK is REAL array, dimension (N)

           INFO      (output)
                     INFO is INTEGER
                     = 0:  successful exit
                     < 0:  if INFO = -i, the i-th argument had an illegal value



LAPACK routine                  31 October 2017                      CPTCON(3)