ZPBCON  -  estimate the reciprocal of the condition number
       (in the 1-norm) of a complex Hermitian  positive  definite
       band matrix using the Cholesky factorization A = U**H*U or
       A = L*L**H computed by ZPBTRF


SYNOPSIS

       SUBROUTINE ZPBCON( UPLO, N, KD, AB,  LDAB,  ANORM,  RCOND,
                          WORK, RWORK, INFO )

           CHARACTER      UPLO

           INTEGER        INFO, KD, LDAB, N

           DOUBLE         PRECISION ANORM, RCOND

           DOUBLE         PRECISION RWORK( * )

           COMPLEX*16     AB( LDAB, * ), WORK( * )


PURPOSE

       ZPBCON  estimates  the  reciprocal of the condition number
       (in the 1-norm) of a complex Hermitian  positive  definite
       band matrix using the Cholesky factorization A = U**H*U or
       A = L*L**H computed by ZPBTRF.  An  estimate  is  obtained
       for norm(inv(A)), and the reciprocal of the condition num­
       ber is computed as RCOND = 1 / (ANORM * norm(inv(A))).


ARGUMENTS

       UPLO    (input) CHARACTER*1
               = 'U':  Upper triangular factor stored in AB;
               = 'L':  Lower triangular factor stored in AB.

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

       KD      (input) INTEGER
               The number of superdiagonals of the  matrix  A  if
               UPLO = 'U', or the number of sub-diagonals if UPLO
               = 'L'.  KD >= 0.

       AB      (input) COMPLEX*16 array, dimension (LDAB,N)
               The triangular factor U or  L  from  the  Cholesky
               factorization A = U**H*U or A = L*L**H of the band
               matrix A, stored in the first  KD+1  rows  of  the
               array.  The j-th column of U or L is stored in the
               j-th column of the array AB as  follows:  if  UPLO
               ='U',   AB(kd+1+i-j,j)   =   U(i,j)  for  max(1,j-
               kd)<=i<=j; if UPLO ='L', AB(1+i-j,j)     =  L(i,j)
               for j<=i<=min(n,j+kd).

       LDAB    (input) INTEGER
               The  leading  dimension  of the array AB.  LDAB >=


       ANORM   (input) DOUBLE PRECISION
               The 1-norm (or  infinity-norm)  of  the  Hermitian
               band matrix A.

       RCOND   (output) 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    (workspace) COMPLEX*16 array, dimension (2*N)

       RWORK   (workspace) DOUBLE PRECISION array, dimension (N)

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


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