Provided by: liblapack-doc_3.3.1-1_all

**NAME**

LAPACK-3 - 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'

**SYNOPSIS**

SUBROUTINE SLARRC( JOBT, N, VL, VU, D, E, PIVMIN, EIGCNT, LCNT, RCNT, INFO ) CHARACTER JOBT INTEGER EIGCNT, INFO, LCNT, N, RCNT REAL PIVMIN, VL, VU REAL D( * ), E( * )

**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'.

**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) REAL 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 LAPACK auxiliary routine (version 3.2.2) April 2011 SLARRC(3lapack)