source: issm/trunk-jpl/src/jl/core/solutionsequences.jl@ 26725

function solutionsequence_nonlinear(femmodel::FemModel,analysis::Analysis,maxiter::Int64,restol::Float64,reltol::Float64,abstol::Float64) # {{{

        #Initialize number of iterations
        count = 0
        converged = false

        #Get existing solution
        ug = GetSolutionFromInputsx(analysis,femmodel)
        uf = Reducevectorgtofx(ug,femmodel.nodes)

        #Update once again the solution to make sure that vx and vxold are similar (for next step in transient or steadystate)
        InputUpdateFromSolutionx(analysis,ug,femmodel)

        #Loop until we reach convergence
        while(~converged)

                #Get new matrices
                Kff, Kfs, pf = SystemMatricesx(femmodel,analysis)

                #Enforce constraints
                ys = CreateNodalConstraintsx(femmodel.nodes)
                Reduceloadx!(pf, Kfs, ys)

                #Solve!
                old_uf = uf
                uf = Solverx(Kff, pf, old_uf)

                #Merge uf with ys
                Mergesolutionfromftogx(ug, uf, ys, femmodel.nodes)

                #Check for convergence
                converged = convergence(Kff,pf,uf,old_uf,restol,reltol,abstol)
                InputUpdateFromSolutionx(analysis,ug,femmodel)

                #Increase count
                count += 1
                if(count>=maxiter)
                        println("   maximum number of nonlinear iterations (",maxiter,") exceeded")
                        converged = true
                end
        end

        print("\n   total number of iterations: ",  count,  "\n")

end# }}}
function convergence(Kff::IssmMatrix, pf::IssmVector, uf::IssmVector, old_uf::IssmVector, restol::Float64, reltol::Float64, abstol::Float64)#{{{

        print("   checking convergence\n");

        #If solution vector is empty, return true
        if(IsEmpty(uf))
                return true
        end

        #Convergence criterion #1: force equilibrium (Mandatory)
        #compute K[n]U[n-1] - F
        KUold  = Duplicate(uf);    MatMult!(Kff,old_uf,KUold)
        KUoldF = Duplicate(KUold); VecCopy!(KUold, KUoldF); AXPY!(KUoldF, -1.0, pf)
        nKUoldF = Norm(KUoldF,2)
        nF      = Norm(pf,2)
        res = nKUoldF/nF
        if ~isfinite(res)
                println("norm nf = ", nF, " and norm kuold = ",nKUoldF)
                error("mechanical equilibrium convergence criterion is not finite!")
        end
        if(res<restol)
                print("   mechanical equilibrium convergence criterion ", res*100, " < ", restol*100, " %\n")
                converged=true
        else
                print("   mechanical equilibrium convergence criterion ", res*100, " > ", restol*100, " %\n")
                converged=false;
        end

        #Convergence criterion #2: norm(du)/norm(u)
        if ~isnan(reltol)
                duf = Duplicate(old_uf); VecCopy!(old_uf,duf); AXPY!(duf, -1.0, uf)
                ndu = Norm(duf, 2); nu = Norm(old_uf, 2)
                if ~isfinite(ndu) | ~isfinite(nu) 
                        error("convergence criterion is not finite!")
                end
                if((ndu/nu)<reltol)
                        print("   Convergence criterion: norm(du)/norm(u)      ", ndu/nu*100, " < ", reltol*100, " %\n")
                else
                        print("   Convergence criterion: norm(du)/norm(u)      ", ndu/nu*100, " > ", reltol*100, " %\n")
                        converged=false;
                end
        end

        #Convergence criterion #3: max(du)
        if ~isnan(abstol)
                duf = Duplicate(old_uf); VecCopy!(old_uf,duf); AXPY!(duf, -1.0, uf)
                nduinf= Norm(duf, 3)
                if ~isfinite(nduinf) 
                        error("convergence criterion is not finite!")
                end
                if(nduinf<abstol)
                        print("   Convergence criterion: max(du)               ", nduinf, " < ", abstol, "\n")
                else
                        print("   Convergence criterion: max(du)               ", nduinf, " > ", abstol, "\n")
                        converged=false;
                end
        end

        return converged

end#}}}