LAPACK
3.6.1
LAPACK: Linear Algebra PACKage
|
subroutine dlarrc | ( | character | JOBT, |
integer | N, | ||
double precision | VL, | ||
double precision | VU, | ||
double precision, dimension( * ) | D, | ||
double precision, dimension( * ) | E, | ||
double precision | PIVMIN, | ||
integer | EIGCNT, | ||
integer | LCNT, | ||
integer | RCNT, | ||
integer | INFO | ||
) |
DLARRC computes the number of eigenvalues of the symmetric tridiagonal matrix.
Download DLARRC + dependencies [TGZ] [ZIP] [TXT]
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'.
[in] | JOBT | JOBT is CHARACTER*1 = 'T': Compute Sturm count for matrix T. = 'L': Compute Sturm count for matrix L D L^T. |
[in] | N | N is INTEGER The order of the matrix. N > 0. |
[in] | VL | VL is DOUBLE PRECISION The lower bound for the eigenvalues. |
[in] | VU | VU is DOUBLE PRECISION The upper bound for the eigenvalues. |
[in] | D | D is 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. |
[in] | E | E is 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. |
[in] | PIVMIN | PIVMIN is DOUBLE PRECISION The minimum pivot in the Sturm sequence for T. |
[out] | EIGCNT | EIGCNT is INTEGER The number of eigenvalues of the symmetric tridiagonal matrix T that are in the interval (VL,VU] |
[out] | LCNT | LCNT is INTEGER |
[out] | RCNT | RCNT is INTEGER The left and right negcounts of the interval. |
[out] | INFO | INFO is INTEGER |
Definition at line 139 of file dlarrc.f.