DLARRC
November 2006
Purpose
Find the number of eigenvalues of the symmetric tridiagonal matrix T
that are in the interval (VL,VU] if JOBT = 'T', and of L D L^T
if JOBT = 'L'.
that are in the interval (VL,VU] if JOBT = 'T', and of L D L^T
if JOBT = 'L'.
Arguments
| JOBT |
(input) CHARACTER*1
= 'T': Compute Sturm count for matrix T.
= 'L': Compute Sturm count for matrix L D L^T. |
| N |
(input) INTEGER
The order of the matrix. N > 0.
|
| VL |
(input) DOUBLE PRECISION
|
| VU |
(input) DOUBLE PRECISION
The lower and upper bounds for the eigenvalues.
|
| D |
(input) DOUBLE PRECISION array, dimension (N)
JOBT = 'T': The N diagonal elements of the tridiagonal matrix T.
JOBT = 'L': The N diagonal elements of the diagonal matrix D. |
| E |
(input) DOUBLE PRECISION array, dimension (N)
JOBT = 'T': The N-1 offdiagonal elements of the matrix T.
JOBT = 'L': The N-1 offdiagonal elements of the matrix L. |
| PIVMIN |
(input) DOUBLE PRECISION
The minimum pivot in the Sturm sequence for T.
|
| EIGCNT |
(output) INTEGER
The number of eigenvalues of the symmetric tridiagonal matrix T
that are in the interval (VL,VU] |
| LCNT |
(output) INTEGER
|
| RCNT |
(output) INTEGER
The left and right negcounts of the interval.
|
| INFO |
(output) INTEGER
|
Further Details
Based on contributions by
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
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