adaptive algorithm
in [Matlab]
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From: Oluwa KuIse on 25 May 2010 10:08 Hello, I want to have a program that can increase or decrease my time step as appropriate. The main program is: t = 0; %initialize time T = 2000; %Simulation Time in seconds del_t = 1 ; %arbitrarily chosen, as the program develops, we will get a better 1st estimate grid_size = 5; %assume the DEM has a resolution of 5meters g = 9.81; H_o = 0.001*ones(11,10); %fluid depth U_o = zeros(11,10); % x-direction flux V_o = zeros(11,10); % y-direction flux Z =10*ones(11,10); % sample topography R = 0.01*ones(11,10); % rainfall I = 0.001*ones(11,10); %infiltration t = t + del_t; while t < T [H_c,U_c,V_c] = operator(H_o,U_o,V_o,Z,R,I,del_t,grid_size); %this calls the function "operator" t = t + del_t; end Error is defined as norm((H_c-H_o)./H_o) and the Tolerance is 1e-3. The pseudo code I am having difficulty with translating into MATLAB is: if Error < 0.5*Tol Accept current solution, and increase the size (of del_t) at the next step esleif Error is between 0.5*Tol and Tol Accept current solution, and hold the size (of del_t) at the next step esleif Error is between Tol and 2*Tol Accept current solution, and but decrease the size (of del_t) at the next step elseif Error > 2*Tol Throw current results away, cut the step size in half and retry How do I implement this algorithm in the context of my program in Matlab? Thank you, Michael |