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annotate +time/Rungekutta4.m @ 984:0585a2ee7ee7 feature/timesteppers

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Inline the rk.rungekutta_4 function.
author Jonatan Werpers <jonatan@werpers.com>
date Tue, 08 Jan 2019 12:19:33 +0100
parents b89379fb0814
children a99f00896b8e
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1 classdef Rungekutta4 < time.Timestepper
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2 properties
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3 F
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4 dt
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5 t
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6 v
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7 n
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8 end
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11 methods
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12 % Create a time stepper for
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13 % v_t = F(t,v), v(t0) = v0
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14 % with step size dt.
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15 function obj = Rungekutta4(F, dt, t0, v0)
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16 obj.F = F;
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17 obj.dt = dt;
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18 obj.t = t0;
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19 obj.v = v0;
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20 obj.n = 0;
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21 end
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22
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23 function [v,t] = getV(obj)
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24 v = obj.v;
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25 t = obj.t;
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26 end
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28 function obj = step(obj)
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29 v = obj.v;
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30 dt = obj.dt;
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31
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32 k1 = obj.F(t, v);
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33 k2 = obj.F(t + 0.5*dt, v + 0.5*dt*k1);
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34 k3 = obj.F(t + 0.5*dt, v + 0.5*dt*k2);
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35 k4 = obj.F(t + dt, v + dt*k3);
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36
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37 obj.v = v + dt*(1/6)*(k1+2*(k2+k3)+k4);
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38 obj.t = obj.t + obj.dt;
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39 obj.n = obj.n + 1;
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40 end
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41 end
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42
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43 methods (Static)
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44 function dt = getTimeStep(lambda)
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45 dt = rk4.get_rk4_time_step(lambda);
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46 end
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47 end
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48 end