!>
!> ZPBSTF computes a split Cholesky factorization of a complex
!> Hermitian positive definite band matrix A.
!>
!> This routine is designed to be used in conjunction with ZHBGST.
!>
!> The factorization has the form  A = S**H*S  where S is a band matrix
!> of the same bandwidth as A and the following structure:
!>
!>   S = ( U    )
!>       ( M  L )
!>
!> where U is upper triangular of order m = (n+kd)/2, and L is lower
!> triangular of order n-m.
!> 

UPLO

!>          UPLO is CHARACTER*1
!>          = 'U':  Upper triangle of A is stored;
!>          = 'L':  Lower triangle of A is stored.
!> 

N

!>          N is INTEGER
!>          The order of the matrix A.  N >= 0.
!> 

KD

!>          KD is INTEGER
!>          The number of superdiagonals of the matrix A if UPLO = 'U',
!>          or the number of subdiagonals if UPLO = 'L'.  KD >= 0.
!> 

AB

!>          AB is COMPLEX*16 array, dimension (LDAB,N)
!>          On entry, the upper or lower triangle of the Hermitian band
!>          matrix A, stored in the first kd+1 rows of the array.  The
!>          j-th column of A is stored in the j-th column of the array AB
!>          as follows:
!>          if UPLO = 'U', AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j;
!>          if UPLO = 'L', AB(1+i-j,j)    = A(i,j) for j<=i<=min(n,j+kd).
!>
!>          On exit, if INFO = 0, the factor S from the split Cholesky
!>          factorization A = S**H*S. See Further Details.
!> 

LDAB

!>          LDAB is INTEGER
!>          The leading dimension of the array AB.  LDAB >= KD+1.
!> 

INFO

!>          INFO is INTEGER
!>          = 0: successful exit
!>          < 0: if INFO = -i, the i-th argument had an illegal value
!>          > 0: if INFO = i, the factorization could not be completed,
!>               because the updated element a(i,i) was negative; the
!>               matrix A is not positive definite.
!> 

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!>
!>  The band storage scheme is illustrated by the following example, when
!>  N = 7, KD = 2:
!>
!>  S = ( s11  s12  s13                     )
!>      (      s22  s23  s24                )
!>      (           s33  s34                )
!>      (                s44                )
!>      (           s53  s54  s55           )
!>      (                s64  s65  s66      )
!>      (                     s75  s76  s77 )
!>
!>  If UPLO = 'U', the array AB holds:
!>
!>  on entry:                          on exit:
!>
!>   *    *   a13  a24  a35  a46  a57   *    *   s13  s24  s53**H s64**H s75**H
!>   *   a12  a23  a34  a45  a56  a67   *   s12  s23  s34  s54**H s65**H s76**H
!>  a11  a22  a33  a44  a55  a66  a77  s11  s22  s33  s44  s55    s66    s77
!>
!>  If UPLO = 'L', the array AB holds:
!>
!>  on entry:                          on exit:
!>
!>  a11  a22  a33  a44  a55  a66  a77  s11    s22    s33    s44  s55  s66  s77
!>  a21  a32  a43  a54  a65  a76   *   s12**H s23**H s34**H s54  s65  s76   *
!>  a31  a42  a53  a64  a64   *    *   s13**H s24**H s53    s64  s75   *    *
!>
!>  Array elements marked * are not used by the routine; s12**H denotes
!>  conjg(s12); the diagonal elements of S are real.
!>