classdef Rungekutta4RV < time.Timestepper
    properties
        F
        k
        t
        v
        m
        n

        % Additional members used for the RV update
        RV
    end


    methods
        function obj = Rungekutta4RV(F, k, t0, v0, RV)
            obj.F = F;
            obj.k = k;
            obj.t = t0;
            obj.v = v0;
            obj.m = length(v0);
            obj.n = 0;
            obj.RV = RV;
        end

        function [v, t] = getV(obj)
            v = obj.v;
            t = obj.t;
        end

        function state = getState(obj)
            [residual, u_t, f_x] = obj.RV.getResidual();
            state = struct('v', obj.v, 'residual', residual, 'u_t', u_t, 'f_x', f_x, 'viscosity', obj.RV.getViscosity(), 't', obj.t);
        end

        function obj = step(obj)
            obj.v = time.rk4.rungekutta_4RV(obj.v, obj.t, obj.k, obj.F, obj.RV);
            obj.t = obj.t + obj.k;
            obj.n = obj.n + 1;
        end
    end


    methods (Static)
        function k = getTimeStep(lambda)
            k = rk4.get_rk4_time_step(lambda);
        end
    end

end