## [Libmesh-users] Set Initial Guess for a Nonlinear Problem

 [Libmesh-users] Set Initial Guess for a Nonlinear Problem From: Dafang Wang - 2013-09-10 23:04:45 ```Hi, I am a new user who has been using Libmesh for about 6 months on biomechanical problems. Does anyone know how to set the initial guess for a nonlinear equation by designating a known vector to be the initial guess? I am using the NonlinearImplicitSystem Class in the following manner: NonlinearImplicitSystem system. Vector soln; loop Step 1: // use soln as the initial guess for the system Step 2: system.solve(); Step 3: soln = system.solution(); Step 4: //update system end My goal is to repeatedly solve the nonlinear system, with each iteration using the solution of its previous iteration as the initial guess. I am wondering which particular member functions or member variables I should use. Any comments or suggestions would be greatly appreciated. Thank you very much for your help. Best, Dafang -- Dafang Wang, Ph.D. Postdoctoral Fellow Institute of Computational Medicine Hackerman Hall, Room 218 Johns Hopkins University, Baltimore, 21218 http://lagniappe.icm.jhu.edu/~dwang/ ```

 [Libmesh-users] Set Initial Guess for a Nonlinear Problem From: Dafang Wang - 2013-09-10 23:04:45 ```Hi, I am a new user who has been using Libmesh for about 6 months on biomechanical problems. Does anyone know how to set the initial guess for a nonlinear equation by designating a known vector to be the initial guess? I am using the NonlinearImplicitSystem Class in the following manner: NonlinearImplicitSystem system. Vector soln; loop Step 1: // use soln as the initial guess for the system Step 2: system.solve(); Step 3: soln = system.solution(); Step 4: //update system end My goal is to repeatedly solve the nonlinear system, with each iteration using the solution of its previous iteration as the initial guess. I am wondering which particular member functions or member variables I should use. Any comments or suggestions would be greatly appreciated. Thank you very much for your help. Best, Dafang -- Dafang Wang, Ph.D. Postdoctoral Fellow Institute of Computational Medicine Hackerman Hall, Room 218 Johns Hopkins University, Baltimore, 21218 http://lagniappe.icm.jhu.edu/~dwang/ ```
 Re: [Libmesh-users] Set Initial Guess for a Nonlinear Problem From: subramanya sadasiva - 2013-09-11 05:43:34 ```I think the vector in system.solution or system.current_local_solution is automatically used as an initial guess.  ---------------------------------------- > Date: Tue, 10 Sep 2013 18:04:18 -0400 > From: dafang.wang@... > To: libmesh-users@... > Subject: [Libmesh-users] Set Initial Guess for a Nonlinear Problem > > Hi, > > I am a new user who has been using Libmesh for about 6 months on biomechanical problems. > > Does anyone know how to set the initial guess for a nonlinear equation by designating a > known vector to be the initial guess? I am using the NonlinearImplicitSystem Class in the > following manner: > > NonlinearImplicitSystem system. > Vector soln; > loop > Step 1: // use soln as the initial guess for the system > Step 2: system.solve(); > Step 3: soln = system.solution(); > Step 4: //update system > end > > My goal is to repeatedly solve the nonlinear system, with each iteration using the > solution of its previous iteration as the initial guess. I am wondering which particular > member functions or member variables I should use. > > Any comments or suggestions would be greatly appreciated. Thank you very much for your help. > > Best, > Dafang > -- > Dafang Wang, Ph.D. > Postdoctoral Fellow > Institute of Computational Medicine > Hackerman Hall, Room 218 > Johns Hopkins University, Baltimore, 21218 > http://lagniappe.icm.jhu.edu/~dwang/ > > ------------------------------------------------------------------------------ > How ServiceNow helps IT people transform IT departments: > 1. Consolidate legacy IT systems to a single system of record for IT > 2. Standardize and globalize service processes across IT > 3. Implement zero-touch automation to replace manual, redundant tasks > http://pubads.g.doubleclick.net/gampad/clk?id=51271111&iu=/4140/ostg.clktrk > _______________________________________________ > Libmesh-users mailing list > Libmesh-users@... > https://lists.sourceforge.net/lists/listinfo/libmesh-users ```