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NAME
     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( * )



     #include <sunperf.h>

     void zpbcon(char uplo, int n, int  kd,  doublecomplex  *zab,
               int   ldab,  double  anorm,  double  *drcond,  int
               *info);

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 number 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  >=
               KD+1.

     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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