<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE article  PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "http://dtd.nlm.nih.gov/publishing/3.0/journalpublishing3.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" dtd-version="3.0" xml:lang="en" article-type="research article"><front><journal-meta><journal-id journal-id-type="publisher-id">JAMP</journal-id><journal-title-group><journal-title>Journal of Applied Mathematics and Physics</journal-title></journal-title-group><issn pub-type="epub">2327-4352</issn><publisher><publisher-name>Scientific Research Publishing</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.4236/jamp.2014.23007</article-id><article-id pub-id-type="publisher-id">JAMP-43185</article-id><article-categories><subj-group subj-group-type="heading"><subject>Articles</subject></subj-group><subj-group subj-group-type="Discipline-v2"><subject>Physics&amp;Mathematics</subject></subj-group></article-categories><title-group><article-title>
 
 
  Application and Generalization of Eigenvalues Perturbation Bounds for Hermitian Block Tridiagonal Matrices
 
</article-title></title-group><contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>icheng</surname><given-names>Li</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref><xref ref-type="corresp" rid="cor1"><sup>*</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Jing</surname><given-names>Wu</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Xu</surname><given-names>Kong</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib></contrib-group><aff id="aff1"><addr-line>School of Mathematics and Statistics, Xi’an Jiaotong University, Xi’an, China</addr-line></aff><author-notes><corresp id="cor1">* E-mail:<email>jcli@mail.xjtu.edu.cn(IL)</email>;</corresp></author-notes><pub-date pub-type="epub"><day>10</day><month>02</month><year>2014</year></pub-date><volume>02</volume><issue>03</issue><fpage>60</fpage><lpage>70</lpage><history><date date-type="received"><day>December</day>	<month>15,</month>	<year>2013</year></date><date date-type="rev-recd"><day>January</day>	<month>15,</month>	<year>2014</year>	</date><date date-type="accepted"><day>January</day>	<month>21,</month>	<year>2014</year></date></history><permissions><copyright-statement>&#169; Copyright  2014 by authors and Scientific Research Publishing Inc. </copyright-statement><copyright-year>2014</copyright-year><license><license-p>This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/</license-p></license></permissions><abstract><p>
 
 
   The paper contains two parts. First, by applying the results about the eigenvalue perturbation bounds for Hermitian block tridiagonal matrices in paper [1], we obtain a new efficient method to estimate the perturbation bounds for singular values of block tridiagonal matrix. Second, we consider the perturbation bounds for eigenvalues of Hermitian matrix with block tridiagonal structure when its two adjacent blocks are perturbed simultaneously. In this case, when the eigenvalues of the perturbed matrix are well-separated from the spectrum of the diagonal blocks, our eigenvalues perturbation bounds are very sharp. The numerical examples illustrate the efficiency of our methods. 
 
</p></abstract><kwd-group><kwd>Singular Value; Eigenvalue Perturbation; Hermitian Matrix; Block Tridiagonal Matrix; Eigenvector</kwd></kwd-group></article-meta></front><body><sec id="s1"><title>NOTES</title><disp-formula id="scirp.43185-formula131496"><graphic  xlink:href="http://html.scirp.org/file/7-1720084x14.png"  xlink:type="simple"/></disp-formula><p><sup>*</sup>The work was supported by the Fundamental Research Funds for the Central Universities (xjj20100114) and the National Natural Science Foundation of China (11171270).</p><p><sup>#</sup>Corresponding author.</p></sec></body><back><ref-list><title>References</title><ref id="scirp.43185-ref1"><label>1</label><mixed-citation publication-type="other" xlink:type="simple">Y. Nakatsukasa, “Eigenvalue Perturbation Bounds for Hermitian Block Tridiagonal Matrices,” Applied Numerical Mathematics, Vol. 62, No. 1, 2012, pp. 67-78.</mixed-citation></ref><ref id="scirp.43185-ref2"><label>2</label><mixed-citation publication-type="other" xlink:type="simple">G. W. Stewart and J.-G. Sun, “Matrix Perturbation Theory,” Academic Press, Boston, 1990.</mixed-citation></ref><ref id="scirp.43185-ref3"><label>3</label><mixed-citation publication-type="other" xlink:type="simple">J. Demmel, “Applied Numerical Linear Algebra,” SIAM, Philadelphia, 1997.</mixed-citation></ref><ref id="scirp.43185-ref4"><label>4</label><mixed-citation publication-type="other" xlink:type="simple">G. H. Golub and C. F. Van Loan, “Matrix Computations,” Johns Hopkins University Press, Baltimore, 1996.</mixed-citation></ref><ref id="scirp.43185-ref5"><label>5</label><mixed-citation publication-type="other" xlink:type="simple">E.-X. Jiang, “Perturbation in Eigenvalues of a Symmetric Tridiagonal Matrix,” Linear Algebra and its Applications, Vol. 399, 2005, pp. 91-107.</mixed-citation></ref><ref id="scirp.43185-ref6"><label>6</label><mixed-citation publication-type="other" xlink:type="simple">J. Barlow and J. Demmel, “Computing Accurate Eigensystems of Scaled Diagonally Dominant Matrices,” SIAM Journal on Numerical Analysis, Vol. 27, No. 3, 1990, pp. 762-791.</mixed-citation></ref><ref id="scirp.43185-ref7"><label>7</label><mixed-citation publication-type="other" xlink:type="simple">J. Barlow and I. Slapnicar, “Optimal Perturbation Bounds for the Hermitian Eigenvalue Problem,” Linear Algebra and its Applications, Vol. 309, No. 1-3, 2000, pp. 19-43.</mixed-citation></ref><ref id="scirp.43185-ref8"><label>8</label><mixed-citation publication-type="other" xlink:type="simple">C.-K. Li and R.-C. Li, “A Note on Eigenvalues of Perturbed Hermitian Matrices,” Linear Algebra and its Applications, Vol. 395, 2005, pp. 183-190. http://dx.doi.org/10.1016/j.laa.2004.08.026</mixed-citation></ref></ref-list></back></article>