How can I plot ode 45 for different values of a constant after specific time?

Question

Usman Saleem 2019-2-4

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/443076-how-can-i-plot-ode-45-for-different-values-of-a-constant-after-specific-time

评论： Usman Saleem 2019-2-4

I want to change the value of del after given time interval.

T = 1:1:3500;
del = 0;        % For T=1:1:3100
del = 1;        % For T=3100:1:3500
[t,y] = ode45(@f_1,T,C);

This is the only line of the function which contains del.

dy(4,1)=(y(1)*k(1))/V(4) - (y(4)*(k(1) + k(2) + k(3) + del*k_clear))/V(4) + (y(2)*k(2))/V(4) + (y(3)*k(3))/V(4);

I want to plot this graph

But was able to construct this.

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

madhan ravi 2019-2-4

编辑：madhan ravi 2019-2-4

在 MATLAB Online 中打开

Share your ode function.Why not?

function dydt = myod(t,y)
.....
if  t <= 3100
    del = 0;
else
    del = 1;   
end
.... rest of the code
end

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Torsten 2019-2-4

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/443076-how-can-i-plot-ode-45-for-different-values-of-a-constant-after-specific-time#answer_359425

编辑：Torsten 2019-2-4

function main
  T = 1:1:3100;
  del = 0.0;
  [t1,y1] = ode45(@(t,y)f_1(t,y,del),T,C);
  T = 3100:1:3500;
  del = 1.0;
  C = y1(end,:);
  [t2,y2] = ode45(@(t,y)f_1(t,y,del),T,C);
  t = [t1;t2];
  y = [y1;y2];
  plot(t,y)
end
function dy = f_1(t,y,del)
  ...
end