--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/+time/+rk/rungekuttaDiscreteData.m	Mon Dec 03 16:26:18 2018 -0800
@@ -0,0 +1,30 @@
+% Takes one time step of size dt using the rungekutta method
+% starting from @arg v.
+%
+% discreteData contains (a part of) the forcing function, already
+% evaluated on the space-time grid.
+%
+% ODE: dv/dt = F(v,t) + discreteData(:, nt), where nt denotes the current time-point.
+%
+% coeffs is a struct holding the RK coefficients
+% for the specific method.
+% Also returns the stage approximations (V) and stage rates (K).
+function [v, V, K] = rungekuttaDiscreteData(v, t , dt, F, coeffs, discreteData, n)
+    % Compute the intermediate stages k
+    K = zeros(length(v), coeffs.s);
+    V = zeros(length(v), coeffs.s);
+    for i = 1:coeffs.s
+        u = v;
+        for j = 1:i-1
+            u = u + dt*coeffs.a(i,j)*K(:,j);
+        end
+        V(:,i) = u;
+        K(:,i) = F(u,t+coeffs.c(i)*dt);
+        K(:,i) = K(:,i) + discreteData(:, n*coeffs.s + i);
+    end
+    % Compute the updated solution as a linear combination
+    % of the intermediate stages.
+    for i = 1:coeffs.s
+        v = v + dt*coeffs.b(i)*k(:,i);
+    end
+end
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