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



NAME
       ZSPCON

SYNOPSIS
       SUBROUTINE ZSPCON (UPLO, N, AP, IPIV, ANORM, RCOND, WORK, INFO)



PURPOSE
            ZSPCON estimates the reciprocal of the condition number (in the
            1-norm) of a complex symmetric packed matrix A using the
            factorization A = U*D*U**T or A = L*D*L**T computed by ZSPTRF.

            An estimate is obtained for norm(inv(A)), and the reciprocal of the
            condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).




ARGUMENTS
           UPLO      (input)
                     UPLO is CHARACTER*1
                     Specifies whether the details of the factorization are stored
                     as an upper or lower triangular matrix.
                     = 'U':  Upper triangular, form is A = U*D*U**T;
                     = 'L':  Lower triangular, form is A = L*D*L**T.

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

           AP        (input)
                     AP is COMPLEX*16 array, dimension (N*(N+1)/2)
                     The block diagonal matrix D and the multipliers used to
                     obtain the factor U or L as computed by ZSPTRF, stored as a
                     packed triangular matrix.

           IPIV      (input)
                     IPIV is INTEGER array, dimension (N)
                     Details of the interchanges and the block structure of D
                     as determined by ZSPTRF.

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

           RCOND     (output)
                     RCOND is DOUBLE PRECISION
                     The reciprocal of the condition number of the matrix A,
                     computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
                     estimate of the 1-norm of inv(A) computed in this routine.

           WORK      (output)
                     WORK is COMPLEX*16 array, dimension (2*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                      ZSPCON(3)