将其他依赖于迭代的输入传递给ode45 [英] Passing additional iteration-dependent inputs to ode45

问题描述

我正在尝试使用ode45函数求解微分方程.考虑以下代码，

I'm trying to solve differential equation using the ode45 function. Consider the following code,

[t1,X2] = ode45(@(t,x)fun(t,x,C1,C2,C3,C4),t0,X01);

其中参数C1，C2，C3和C4是列向量，对于ode45所引用的功能(fun.m)应该可用.我希望值在每次迭代后都发生变化，例如，在开始时，我要输入的C1项是C1(1)，在下一次迭代中是C1(2)，依此类推.

where parameters C1, C2, C3 and C4 are column vectors, which should be available to the function that ode45 is referring to (fun.m). I want the values to change after every iteration, so for example, at the beginning the entry of C1 I want in is C1(1), in the next iteration it's C1(2), etc.

我该如何实现?

推荐答案

您可能已经注意到

You may have noticed that the official docs are not too helpful in this scenario (as they pretty much force you to use global variables - which is doable, but discouraged). Instead, I'll show you how this can be done with classes and function handles. Consider the following:

classdef SimpleQueue < handle
  %SIMPLEQUEUE A simple FIFO data structure.

  properties (Access = private)
    data
    position
  end

  methods (Access = public)
    function obj = SimpleQueue(inputData)
      %SIMPLEQUEUE Construct an instance of this class
      obj.data = inputData;
      rewind(obj);
    end % constructor

    function out = pop(obj, howMany)
      %POP return the next howMany elements.
      if nargin < 2 
        howMany = 1; % default amount of values to return
      end
      finalPosition = obj.position + howMany;
      if finalPosition > numel(obj.data)
        error('Too many elements requested!');
      end      
      out = obj.data(obj.position + 1 : obj.position + howMany);
      obj.position = finalPosition;      
    end % pop

    function [] = rewind(obj)
      %REWIND restarts the element tracking
      % Subsequent calls to pop() shall return elements from the beginning.
      obj.position = 0;
    end % rewind
  end % methods  
end % classdef

如何使用它?简单:

C1q = SimpleQueue(C1);
C2q = SimpleQueue(C2);
C3q = SimpleQueue(C3);
C4q = SimpleQueue(C4);

[t1,X2] = ode45(@(t,x)fun(t,x,@C1q.pop,@C2q.pop,@C3q.pop,@C4q.pop),t0,X01);

如您所见，在fun内部，我们使用C1q()而不是C1.

As you can see, inside fun we use C1q() instead of C1.

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