--- a/+time/+rk/General.m	Wed Jan 09 10:59:38 2019 +0100
+++ b/+time/+rk/General.m	Wed Jan 09 11:14:16 2019 +0100
@@ -13,10 +13,10 @@
 
 
     methods
-        % Timesteps v_t = F(v,t), using the specified RK method from t = t0 with
-        % timestep dt and initial conditions v = v0
-        function obj = General(F, dt, t0, v0, method, discreteData)
-            default_arg('method',"rk4");
+        % Timesteps v_t = F(v,t), using the specified ButcherTableau
+        % from t = t0 with timestep dt and initial conditions v(0) = v0
+        function obj = General(F, dt, t0, v0, bt, discreteData)
+            assertType(bt, 'time.rk.ButcherTableau')
             default_arg('discreteData', []);
             obj.F = F;
             obj.dt = dt;
@@ -24,10 +24,8 @@
             obj.v = v0;
             obj.n = 0;
 
-            % Extract the coefficients for the specified method
-            % used for the RK updates from the Butcher tableua.
-            [s,a,b,c] = time.rk.butcherTableauFromStr(method);
-            obj.coeffs = struct('s',s,'a',a,'b',b,'c',c);
+            assert(bt.isExplicit())
+            obj.coeffs = struct('s',bt.nStages,'a',bt.a(:,1:end-1),'b',bt.b,'c',bt.c);
 
             if isempty(discreteData)
                 obj.scheme = @(v,t,n) time.rk.rungekutta(v, t, dt, F, obj.coeffs);
@@ -78,4 +76,19 @@
             weights = repmat(b', N, 1);
         end
     end
-end
\ No newline at end of file
+
+    methods(Static)
+        % TBD: Function name
+        function ts = methodFromStr(F, dt, t0, v0, methodStr, discreteData)
+            default_arg('discreteData', []);
+
+            try
+                bt = time.rk.ButcherTableau.(method);
+            catch
+                error('Runge-Kutta method ''%s'' is not implemented', methodStr)
+            end
+
+            ts = time.rk.General(F, dt, t0, v0, bt, discreteData);
+        end
+    end
+end