LAPACK 3.12.0
LAPACK: Linear Algebra PACKage
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◆ slarrr()

subroutine slarrr ( integer  n,
real, dimension( * )  d,
real, dimension( * )  e,
integer  info 
)

SLARRR performs tests to decide whether the symmetric tridiagonal matrix T warrants expensive computations which guarantee high relative accuracy in the eigenvalues.

Download SLARRR + dependencies [TGZ] [ZIP] [TXT]

Purpose:
 Perform tests to decide whether the symmetric tridiagonal matrix T
 warrants expensive computations which guarantee high relative accuracy
 in the eigenvalues.
Parameters
[in]N
          N is INTEGER
          The order of the matrix. N > 0.
[in]D
          D is REAL array, dimension (N)
          The N diagonal elements of the tridiagonal matrix T.
[in,out]E
          E is REAL array, dimension (N)
          On entry, the first (N-1) entries contain the subdiagonal
          elements of the tridiagonal matrix T; E(N) is set to ZERO.
[out]INFO
          INFO is INTEGER
          INFO = 0(default) : the matrix warrants computations preserving
                              relative accuracy.
          INFO = 1          : the matrix warrants computations guaranteeing
                              only absolute accuracy.
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Contributors:
Beresford Parlett, University of California, Berkeley, USA
Jim Demmel, University of California, Berkeley, USA
Inderjit Dhillon, University of Texas, Austin, USA
Osni Marques, LBNL/NERSC, USA
Christof Voemel, University of California, Berkeley, USA