LAPACK  3.4.2
LAPACK: Linear Algebra PACKage
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ssterf.f File Reference

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Functions/Subroutines

subroutine ssterf (N, D, E, INFO)
 SSTERF

Function/Subroutine Documentation

subroutine ssterf ( integer  N,
real, dimension( * )  D,
real, dimension( * )  E,
integer  INFO 
)

SSTERF

Download SSTERF + dependencies [TGZ] [ZIP] [TXT]
Purpose: 
 SSTERF computes all eigenvalues of a symmetric tridiagonal matrix
 using the Pal-Walker-Kahan variant of the QL or QR algorithm.
Parameters:
[in]N
          N is INTEGER
          The order of the matrix.  N >= 0.
[in,out]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.
[in,out]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.
[out]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.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011

Definition at line 87 of file ssterf.f.

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