# dlarrc.f man page

dlarrc.f

## Synopsis

### Functions/Subroutines

subroutine **dlarrc** (JOBT, **N**, VL, VU, D, E, PIVMIN, EIGCNT, LCNT, RCNT, INFO)**DLARRC** computes the number of eigenvalues of the symmetric tridiagonal matrix.

## Function/Subroutine Documentation

### 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.

**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'.

**Parameters:***JOBT*JOBT is CHARACTER*1 = 'T': Compute Sturm count for matrix T. = 'L': Compute Sturm count for matrix L D L^T.

*N*N is INTEGER The order of the matrix. N > 0.

*VL*VL is DOUBLE PRECISION The lower bound for the eigenvalues.

*VU*VU is DOUBLE PRECISION The upper bound for the eigenvalues.

*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.

*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.

*PIVMIN*PIVMIN is DOUBLE PRECISION The minimum pivot in the Sturm sequence for T.

*EIGCNT*EIGCNT is INTEGER The number of eigenvalues of the symmetric tridiagonal matrix T that are in the interval (VL,VU]

*LCNT*LCNT is INTEGER

*RCNT*RCNT is INTEGER The left and right negcounts of the interval.

*INFO*INFO is INTEGER

**Author:**Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**June 2016

**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

Definition at line 139 of file dlarrc.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dlarrc(3) is an alias of dlarrc.f(3).