ODE45 - Programmers Heaven

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# ODE45

Posts: 3Member
[color=Blue]Hi everyone! This is my first time I approach to thi solver and a function. Infact I tried to solve my ODE, but it doesn't work.
Please, would you like to help me?
This is my functin:

N.B. i put the data in "datinuscita" file[/color]

function xp=sloshing(t,S)
%scrivi la funzione con il tempo e lo spostamento iniziale

%xp=zeros(2,1);
%xp(1)=S(2)
xp=-omega_s^2*S+omega*mu/ms*d0*sin(omega*t)

end

[color=Blue]and the solver is:
[/color]
clc

tspan = linspace(0,20,101);
y0=[0,0]
[t,S] = ode45(sloshing, tspan, y0);

% Plot of the solution
plot(t,S(:,1))
xlabel('t')
ylabel('solution y')
title('sloshing vassel').

[/color]

• Posts: 217Member
why "it doesn't work"? does it give you some error? please, attach some test input data so that I can try the code and check where is the problem.
• Posts: 3Member
Hello giug!! Many thanks to answer quickly!
I have attached all my file. You can find the file to input data and a file where they are stored. There are also the function "sloshing" and the solver "sloshingsolv".

This is the error messege:

??? Input argument "S" is undefined.

Error in ==> sloshing at 7
xp=-omega_s^2*S+omega*mu/ms*d0*sin(omega*t)

Error in ==> sloshigosolv at 5
[t,S] = ode45(sloshing, tspan, y0);

Looking forword to hear from you!

• Posts: 217Member
I think that one error is that you miss the function handle @.

you have to call the function in this way (you can see the matlab help to verify it).

[t,S] = ode45([b]@[/b]sloshing, tspan, y0);