--- a/+time/Cdiff.m	Thu Jun 30 14:10:26 2016 +0200
+++ b/+time/Cdiff.m	Thu Jun 30 14:43:43 2016 +0200
@@ -12,22 +12,20 @@
 
 
     methods
+        % Solves u_tt = Du + Eu_t + S
+        % D, E, S can either all be constants or all be function handles,
+        % They can also be omitted by setting them equal to the empty matrix.
+        % Cdiff(D, E, S, k, t0, n0, v, v_prev)
         function obj = Cdiff(D, E, S, k, t0, n0, v, v_prev)
-            % Cdiff(D, E, S, k, t0, n0, v, v_prev)
-            m = size(D,1);
+            m = length(v);
             default_arg('E',sparse(m,m));
             default_arg('S',sparse(m,1));
 
-            if ~(issparse(D) && issparse(E) && issparse(S))
-                warning('One of the matrices D, E, S is not sparse!')
-                print_issparse(D)
-                print_issparse(E)
-                print_issparse(S)
-            end
-
             obj.D = D;
             obj.E = E;
             obj.S = S;
+
+
             obj.k = k;
             obj.t = t0;
             obj.n = n0;

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+time/CdiffTimeDep.m	Thu Jun 30 14:43:43 2016 +0200
@@ -0,0 +1,51 @@
+classdef CdiffTimeDep < time.Timestepper
+    properties
+        D
+        E
+        S
+        k
+        t
+        v
+        v_prev
+        n
+    end
+
+
+    methods
+        % Solves u_tt = Du + E(t)u_t + S(t)
+        % D, E, S can either all be constants or all be function handles,
+        % They can also be omitted by setting them equal to the empty matrix.
+        % CdiffTimeDep(D, E, S, k, t0, n0, v, v_prev)
+        function obj = CdiffTimeDep(D, E, S, k, t0, n0, v, v_prev)
+            m = length(v);
+            default_arg('E', @(t)sparse(m,m));
+            default_arg('S', @(t)sparse(m,1));
+
+            obj.D = D;
+            obj.E = E;
+            obj.S = S;
+
+            obj.k = k;
+            obj.t = t0;
+            obj.n = n0;
+            obj.v = v;
+            obj.v_prev = v_prev;
+        end
+
+        function [v,t] = getV(obj)
+            v = obj.v;
+            t = obj.t;
+        end
+
+        function [vt,t] = getVt(obj)
+            vt = (obj.v-obj.v_prev)/obj.k; % Could be improved using u_tt = f(u))
+            t = obj.t;
+        end
+
+        function obj = step(obj)
+            [obj.v, obj.v_prev] = time.cdiff.cdiff(obj.v, obj.v_prev, obj.k, obj.D, obj.E(obj.t), obj.S(obj.t));
+            obj.t = obj.t + obj.k;
+            obj.n = obj.n + 1;
+        end
+    end
+end
\ No newline at end of file