!>
!> SSTERF computes all eigenvalues of a symmetric tridiagonal matrix
!> using the Pal-Walker-Kahan variant of the QL or QR algorithm.
!> 

N

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

D

!>          D is REAL array, dimension (N)
!>          On entry, the n diagonal elements of the tridiagonal matrix.
!>          On exit, if INFO = 0, the eigenvalues in ascending order.
!> 

E

!>          E is REAL array, dimension (N-1)
!>          On entry, the (n-1) subdiagonal elements of the tridiagonal
!>          matrix.
!>          On exit, E has been destroyed.
!> 

INFO

!>          INFO is INTEGER
!>          = 0:  successful exit
!>          < 0:  if INFO = -i, the i-th argument had an illegal value
!>          > 0:  the algorithm failed to find all of the eigenvalues in
!>                a total of 30*N iterations; if INFO = i, then i
!>                elements of E have not converged to zero.
!> 

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