Question on Initial value problem - error correction
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Zeynep Toprak
le 24 Avr 2020
Commenté : Zeynep Toprak
le 7 Mai 2020
Question
I create a script
function f = exercise711 (t, x)
f = t * x.^2;
end
And on the command window, I wrote
>> [t1, x1] = ode45(@exercise711, [0 1], 1);
>> plot(t1, x1)
>> hold on
>> [t2, x2] = ode45(@exercise711, [0 2], 1);
Warning: Failure at t=1.414192e+00. Unable to meet integration tolerances
without reducing the step size below the smallest value allowed
(3.552714e-15) at time t.
In ode45 (line 308)
>> plot(t2, x2)
here, for the interval [0 2], I get an error and the graph is wrong. Why? How can I correct it? Please help me to do this question in a correct way.
Thanks a lot.
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Réponse acceptée
Ameer Hamza
le 24 Avr 2020
Modifié(e) : Ameer Hamza
le 24 Avr 2020
The result is correct, and it was the purpose of the exercise to show that the solution of an ODE can diverge to infinity. If you use symbolic toolbox to solve this equation, you can see that the analytical solution of this ODE is
and at , there is a singularity and the output become infinity. You can see in warning message that the issue also occurs at 1.414... In the interval [0,1] there is no singularity and MATLAB does not give any warning.
6 commentaires
Ameer Hamza
le 7 Mai 2020
That question requires a bit of thinking. I will answer it if I get some ideas.
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