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dlarrj.f(3) LAPACK dlarrj.f(3)NAMEdlarrj.f-SYNOPSISFunctions/Subroutines subroutine dlarrj (N, D, E2, IFIRST, ILAST, RTOL, OFFSET, W, WERR, WORK, IWORK, PIVMIN, SPDIAM, INFO) DLARRJ performs refinement of the initial estimates of the eigenvalues of the matrix T.Function/Subroutine Documentation subroutine dlarrj (integerN, double precision, dimension( * )D, double precision, dimension( * )E2, integerIFIRST, integerILAST, double precisionRTOL, integerOFFSET, double precision, dimension( * )W, double precision, dimension( * )WERR, double precision, dimension( * )WORK, integer, dimension( * )IWORK, double precisionPIVMIN, double precisionSPDIAM, integerINFO) DLARRJ performs refinement of the initial estimates of the eigenvalues of the matrix T. Purpose: Given the initial eigenvalue approximations of T, DLARRJ does bisection to refine the eigenvalues of T, W( IFIRST-OFFSET ) through W( ILAST-OFFSET ), to more accuracy. Initial guesses for these eigenvalues are input in W, the corresponding estimate of the error in these guesses in WERR. During bisection, intervals [left, right] are maintained by storing their mid-points and semi-widths in the arrays W and WERR respectively. Parameters: N N is INTEGER The order of the matrix. D D is DOUBLE PRECISION array, dimension (N) The N diagonal elements of T. E2 E2 is DOUBLE PRECISION array, dimension (N-1) The Squares of the (N-1) subdiagonal elements of T. IFIRST IFIRST is INTEGER The index of the first eigenvalue to be computed. ILAST ILAST is INTEGER The index of the last eigenvalue to be computed. RTOL RTOL is DOUBLE PRECISION Tolerance for the convergence of the bisection intervals. An interval [LEFT,RIGHT] has converged if RIGHT-LEFT.LT.RTOL*MAX(|LEFT|,|RIGHT|). OFFSET OFFSET is INTEGER Offset for the arrays W and WERR, i.e., the IFIRST-OFFSET through ILAST-OFFSET elements of these arrays are to be used. W W is DOUBLE PRECISION array, dimension (N) On input, W( IFIRST-OFFSET ) through W( ILAST-OFFSET ) are estimates of the eigenvalues of L D L^T indexed IFIRST through ILAST. On output, these estimates are refined. WERR WERR is DOUBLE PRECISION array, dimension (N) On input, WERR( IFIRST-OFFSET ) through WERR( ILAST-OFFSET ) are the errors in the estimates of the corresponding elements in W. On output, these errors are refined. WORK WORK is DOUBLE PRECISION array, dimension (2*N) Workspace. IWORK IWORK is INTEGER array, dimension (2*N) Workspace. PIVMIN PIVMIN is DOUBLE PRECISION The minimum pivot in the Sturm sequence for T. SPDIAM SPDIAM is DOUBLE PRECISION The spectral diameter of T. INFO INFO is INTEGER Error flag. Author: Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. Date: September 2012 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 167 of file dlarrj.f.AuthorGenerated automatically by Doxygen for LAPACK from the source code.Version 3.4.2Tue Sep 25 2012 dlarrj.f(3)

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