view +time/Ode45.m @ 87:0a29a60e0b21

In Curve: Rearranged for speed. arc_length_fun is now a property of Curve. If it is not supplied, it is computed via the derivative and spline fitting. Switching to the arc length parameterization is much faster now. The new stuff can be tested with testArcLength.m (which should be deleted after that).
author Martin Almquist <martin.almquist@it.uu.se>
date Sun, 29 Nov 2015 22:23:09 +0100
parents 48b6fb693025
children b5e5b195da1e
line wrap: on
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classdef Ode45 < time.Timestepper
    properties
        F
        k
        t
        w
        m
        D
        E
        S
        M
        C
        n
    end


    methods
        function obj = Ode45(D, E, S, k, t0, v0, v0t)
            obj.D = D;
            obj.E = E;
            obj.S = S;
            obj.m = length(v0);

            I = speye(obj.m);
            O = sparse(obj.m,obj.m);
            obj.M = [O, I; D, E*I]; % Multiply with I to allow 0 as input.

            if S == 0
                obj.C = zeros(2*obj.m,1);
            else
                obj.C = [zeros(obj.m,1), S];
            end

            obj.k = k;
            obj.t = t0;
            obj.w = [v0; v0t];

            obj.F = @(w,t)(obj.M*w + obj.C);
        end

        function [v,t] = getV(obj)
            v = obj.w(1:end/2);
            t = obj.t;
        end

        function [vt,t] = getVt(obj)
            vt = obj.w(end/2+1:end);
            t = obj.t;
        end

        function obj = step(obj)
            [t,w] = ode45(@(t,w)(obj.F(w,t)),[obj.t obj.t+obj.k],obj.w);

            obj.t = t(end);
            obj.w = w(end,:)';
            obj.n = obj.n + 1;
        end
    end


    methods (Static)
        function k = getTimeStep(lambda)
            k = rk4.get_rk4_time_step(lambda);
        end
    end

end