--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+time/Rungekutta4SecondOrder.m	Thu Sep 17 10:12:50 2015 +0200
@@ -0,0 +1,65 @@
+classdef Rungekutta4SecondOrder < time.Timestepper
+    properties
+        F
+        k
+        t
+        w
+        m
+        D
+        E
+        S
+        M
+        C
+        n
+    end
+
+
+    methods
+        function obj = Rungekutta4SecondOrder(D, E, S, k, t0, v0, v0t)
+            obj.D = D;
+            obj.E = E;
+            obj.S = S;
+            obj.m = length(v0);
+
+            I = speye(obj.m);
+            O = sparse(obj.m,obj.m);
+            obj.M = [O, I; D, E*I]; % Multiply with I to allow 0 as input.
+
+            if S == 0
+                obj.C = zeros(2*obj.m,1);
+            else
+                obj.C = [zeros(obj.m,1), S];
+            end
+
+            obj.k = k;
+            obj.t = t0;
+            obj.w = [v0; v0t];
+
+            obj.F = @(w,t)(obj.M*w + obj.C);
+        end
+
+        function [v,t] = getV(obj)
+            v = obj.w(1:end/2);
+            t = obj.t;
+        end
+
+        function [vt,t] = getVt(obj)
+            vt = obj.w(end/2+1:end);
+            t = obj.t;
+        end
+
+        function obj = step(obj)
+            obj.w = time.rk4.rungekutta_4(obj.w, obj.t, obj.k, obj.F);
+            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
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