diff +time/RungekuttaRV.m @ 846:c6fcee3fcf1b feature/burgers1d

Add generalized RungeKutta and RungeKuttaRV class which extracts its coefficients from a butcher tableau, specified on the scheme.
author Vidar Stiernström <vidar.stiernstrom@it.uu.se>
date Thu, 20 Sep 2018 17:51:19 +0200
parents
children ab2e5a24ddde
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+time/RungekuttaRV.m	Thu Sep 20 17:51:19 2018 +0200
@@ -0,0 +1,50 @@
+classdef RungekuttaRV < time.Timestepper
+    properties
+        F       % RHS of the ODE
+        k       % Time step
+        t       % Time point
+        v       % Solution vector
+        n       % Time level
+        RV      % Residual Viscosity
+        coeffs  % The coefficents used for the RK time integration
+    end
+
+    methods
+        function obj = RungekuttaRV(F, k, t0, v0, RV, order)
+            obj.F = F;
+            obj.k = k;
+            obj.t = t0;
+            obj.v = v0;
+            obj.n = 0;
+            obj.RV = RV;
+            % Extract the coefficients for the specified order
+            % used for the RK updates from the Butcher tableua.
+            [s,a,b,c] = time.rk.butcherTableau(order);
+            obj.coeffs = struct('s',s,'a',a,'b',b,'c',c);
+        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.rk.rungekuttaRV(obj.v, obj.t, obj.k, obj.F, obj.RV, obj.coeffs);
+            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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