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slarrj.f(3) LAPACK slarrj.f(3)slarrj.fNAME-Functions/Subroutines subroutine slarrj (N, D, E2, IFIRST, ILAST, RTOL, OFFSET, W, WERR, WORK, IWORK, PIVMIN, SPDIAM, INFO) SLARRJ performs refinement of the initial estimates of the eigenvalues of the matrix T.SYNOPSISFunction/Subroutine Documentation subroutine slarrj (integerN, real, dimension( * )D, real, dimension( * )E2, integerIFIRST, integerILAST, realRTOL, integerOFFSET, real, dimension( * )W, real, dimension( * )WERR, real, dimension( * )WORK, integer, dimension( * )IWORK, realPIVMIN, realSPDIAM, integerINFO) SLARRJ performs refinement of the initial estimates of the eigenvalues of the matrix T. Purpose: Given the initial eigenvalue approximations of T, SLARRJ 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 REAL array, dimension (N) The N diagonal elements of T. E2 E2 is REAL 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 REAL 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 REAL 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 REAL 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 REAL array, dimension (2*N) Workspace. IWORK IWORK is INTEGER array, dimension (2*N) Workspace. PIVMIN PIVMIN is REAL The minimum pivot in the Sturm sequence for T. SPDIAM SPDIAM is REAL 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 slarrj.f.AuthorGenerated automatically by Doxygen for LAPACK from the source code.Version 3.4.2Tue Sep 25 2012 slarrj.f(3)

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