简介:Inthispaper,wepresentasmoothingNewton-likemethodforsolvingnonlinearsystemsofequalitiesandinequalities.Byusingtheso-calledmaxfunction,wetransfertheinequalitiesintoasystemofsemismoothequalities.ThenasmoothingNewton-likemethodisproposedforsolvingthereformulatedsystem,whichonlyneedstosolveonesystemoflinearequationsandtoperformonelinesearchateachiteration.Theglobalandlocalquadraticconvergencearestudiedunderappropriateassumptions.Numericalexamplesshowthatthenewapproachiseffective.
简介:Inthispaperweimprovethetwoversionsofthetwo-sidedprojectedquasi-Newtonmethod-onewasproposedbyNocedal&Overtonin[1]andtheotherwasdiscussedinourpreviouspaper,byintroducingthreedifferentmeritfunctionstomakeinexactone-dimensionalsearches.Itisshownthattheseimprovedquasi-Newtonalgorithmshavegainedglobalconvergencepropertywhichisnotpossessedbytheoriginaltwoalgorithms.
简介:TheHermitianandskew-Hermitiansplitting(HSS)methodisanunconditionallyconvergentiterationmethodforsolvinglargesparsenon-Hermitianpositivedefinitesystemoflinearequations.BymakinguseoftheHSSiterationastheinnersolverfortheNewtonmethod,weestablishaclassofNewton-HSSmethodsforsolvinglargesparsesystemsofnonlinearequationswithpositivedefiniteJacobianmatricesatthesolutionpoints.ForthisclassofinexactNewtonmethods,twotypesoflocalconvergencetheoremsareprovedunderproperconditions,andnumericalresultsaregiventoexaminetheirfeasibilityandeffectiveness.Inaddition,theadvantagesoftheNewton-HSSmethodsovertheNewton-USOR,theNewton-GMRESandtheNewton-GCGmethodsareshownthroughsolvingsystemsofnonlinearequationsarisingfromthefinitedifferencediscretizationofatwo-dimensionalconvection-diffusionequationperturbedbyanonlinearterm.ThenumericalimplementationsalsoshowthataspreconditionersfortheNewton-GMRESandtheNewton-GCGmethodstheHSSiterationoutperformstheUSORiterationinbothcomputingtimeanditerationstep.
简介:InthispaperwereportasparsetruncatedNewtonalgorithmforhandlinglarge-scalesimpleboundnonlinearconstrainedminimixationproblem.ThetruncatedNewtonmethodisusedtoupdatethevariableswithindicesoutsideoftheactiveset,whiletheprojectedgradientmethodisusedtoupdatetheactivevariables.Ateachiterativelevel,thesearchdirectionconsistsofthreeparts,oneofwhichisasubspacetruncatedNewtondirection,theothertwoaresubspacegradientandmodifiedgradientdirections.ThesubspacetruncatedNewtondirectionisobtainedbysolvingasparsesystemoflinearequations.Theglobalconvergenceandquadraticconvergencerateofthealgorithmareprovedandsomenumericaltestsaregiven.
简介:Fortheimprovedtwo-sidedprojectedquasi-Newtonalgorithms,whichwerepresentedinPartI,weproveinthispaperthattheyarelocallyone-steportwo-stepsuperlinearlyconvergent.Numericaltestsarereportedthereafter.ResultsbysolvingasetoftypicalproblemsselectedfromliteraturehavedemonstratedtheextremeimportanceofthesemodificationsinmakingNocedal&Overton’soriginalmethonpractical.Furthermore,theseresultsshowthattheimprovedalgoritnmsareverycompetitiveincomparisonwithsomehighlypraisedsequentialquadraticprogrammingmethods.
简介:Aclassofperiodicinitialvalueproblemsfortwo-dimensionalNewton-Boussinesqequationsareinvestigatedinthispaper.TheNewton-Boussinesqequationsareturnedintotheequivalentintegralequations.Withiterationmethods,thelocalexistenceofthesolutionsisobtained.Usingthemethodofaprioriestimates,theglobalexistenceofthesolutionisproved.
简介:研究了一类奇异的非Newton多方渗流方程整体解存在性和渐进性.通过引进低能量函数的概念,证明了当初值u0(x)具有低能量时,其相应的解是整体存在的,且当t→∞时具有指数增长.
简介:Inthispaper,basedontheimplicitRunge-Kutta(IRK)methods,wederiveaclassofparallelschemethatcanbeimplementedontheparallelcomputerswithNs(Nisapositiveevennumber)processorsefficiently,anddiscusstheiterativelyB-convergenceoftheNewtoniterativeprocessforsolvingthealgebraicequationsofthescheme,secondlywepresentastrategyprovidinginitialvaluesparallellyfortheiterativeprocess.Finally,somenumericalresultsshowthatourparallelschemeishigherefficientasNisnotsolarge.