1SSTERF(1)                LAPACK routine (version 3.2)                SSTERF(1)
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NAME

6       SSTERF  -  computes  all  eigenvalues of a symmetric tridiagonal matrix
7       using the Pal-Walker-Kahan variant of the QL or QR algorithm
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SYNOPSIS

10       SUBROUTINE SSTERF( N, D, E, INFO )
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12           INTEGER        INFO, N
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14           REAL           D( * ), E( * )
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PURPOSE

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

21       N       (input) INTEGER
22               The order of the matrix.  N >= 0.
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24       D       (input/output) REAL array, dimension (N)
25               On  entry,  the  n diagonal elements of the tridiagonal matrix.
26               On exit, if INFO = 0, the eigenvalues in ascending order.
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28       E       (input/output) REAL array, dimension (N-1)
29               On entry, the (n-1) subdiagonal  elements  of  the  tridiagonal
30               matrix.  On exit, E has been destroyed.
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32       INFO    (output) INTEGER
33               = 0:  successful exit
34               < 0:  if INFO = -i, the i-th argument had an illegal value
35               >  0:  the algorithm failed to find all of the eigenvalues in a
36               total of 30*N iterations; if INFO = i, then  i  elements  of  E
37               have not converged to zero.
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41 LAPACK routine (version 3.2)    November 2008                       SSTERF(1)