1SSTERF(1)                LAPACK routine (version 3.1)                SSTERF(1)
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NAME

6       SSTERF  -  all  eigenvalues of a symmetric tridiagonal matrix using the
7       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

22       N       (input) INTEGER
23               The order of the matrix.  N >= 0.
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25       D       (input/output) REAL array, dimension (N)
26               On  entry,  the  n diagonal elements of the tridiagonal matrix.
27               On exit, if INFO = 0, the eigenvalues in ascending order.
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29       E       (input/output) REAL array, dimension (N-1)
30               On entry, the (n-1) subdiagonal  elements  of  the  tridiagonal
31               matrix.  On exit, E has been destroyed.
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33       INFO    (output) INTEGER
34               = 0:  successful exit
35               < 0:  if INFO = -i, the i-th argument had an illegal value
36               >  0:  the algorithm failed to find all of the eigenvalues in a
37               total of 30*N iterations; if INFO = i, then  i  elements  of  E
38               have not converged to zero.
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42 LAPACK routine (version 3.1)    November 2006                       SSTERF(1)