# Dynamic system using ode45

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Michelle Westin on 20 Apr 2020
Commented: Michelle Westin on 21 Apr 2020
Hi,
I need to solve the following function:
h = X(1);
theta = X(2);
beta = X(3);
hd = X(4);
hdd = X(7);
X1 = [X(1);X(2);X(3)];
X2 = [X(4);X(5);X(6)];
X2d = [X(7);X(8);X(9)];
X2d = inv(Mt)*(-Ct*X2-Kt*X1);
end
Where d are dot, so it is a system of differential equations.
How can I solve this? May I use ode45?
Thanks

Muthu on 20 Apr 2020
Edited: Muthu on 20 Apr 2020
You first need to convert this function into a form, which can be passed in ode45
To solve using ode45, you need to have three important inputs -> @equation, timerange, initial condition, options
hence your equation should begin like:
function X2d = dynamics(t, Y, options):
Y contains all the initial conditions of the variables.
options contain the arguements that you might need to pass in.
define the constants inside the function.
Good luck.

#### 1 Comment

Michelle Westin on 21 Apr 2020
Muthu, thank you for yoour answer. Actually I sumarize the problem to post here. There are other functions to generate the matrices I am using.
I will try to implement like you suggested and if I have another problem, I will post here. Also, I will study a bit more about ode45.
Thank you again and regards