Error when using ODE45

Question

Westin Messer 2018-3-7

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/386900-error-when-using-ode45

编辑： Westin Messer 2018-3-7

Hello

I'm trying to write a code to solve a system of differential equations. One of the given conditions is F(0) = f(t). However when I try and implement that in the code I get an error. I believe that's because ode45 only wants variable inputs for the conditions. How do I get around this?

p_max = 50;
t     = 2;   % seconds
T     = 0.2; % seconds
tau   = 2;   % seconds
c     = 5;   % m/s
L     = 10;  % meters
h     = 5;
t = linspace(1,0.2,1000);
for i=1:1000
f(i) = (5/2)*(1-cos(2*pi*t(i)/T));
end
figure(1)
plot(t,f);
syms x y z
% t = x
% r = y
% p = z
F = @(t,x) [x(2); ((c^2)*(100/h^2)) - (1/tau)*x(2)]; 
[t,xa] = ode45(F,[0 20],[f 0]);
figure(2)
plot(t,xa(:,2))
title('y(t)')
xlabel('t'), ylabel('y')

Problem statement:

he series of the 2nd order ODE can be further reduced to a series of 1st order ODE, as shown in equation (40). The ODE system can be numerically solved with Matlab ODE45. Using the values of the parameters described in this paper, develop your matlab code to reproduce the results of Figures 2a and 2b in this paper based on the Maxwell material model.

Equation 40:

Initial Condition function:

Figures 2a and 2b: