Solving Second Order Differential Equations in Matlab

This video describes how to solve second order initial value problems in Matlab, using the ode45 routine. A full res version can be found at http://blanchard.ep.wisc.edu These videos were recorded for a course I teach as part of a distance masters degree. See http://mepp.engr.wisc.edu

Category:

Science & Technology

Tags:

• matlab
• numerical
• differential
• equation

[alpha001ful]

How can define " a function that defines the functions derived on previous slide (the first deivatives of Z and Y)". i think it is not shown here and that is my problem.

[jakeblanchard]

@alpha001ful

It is easiest if you send me a script I can debug. Send it to blanchard "at" engr.wisc.edu

Alternatively, download a sample script from

blanchard "dot" ep "dot" wisc "dot" edu/PublicMatlab/#IVP

[tomtomtramp]

I've been using your videos, thanks!. But, I think I'm writing the wrong code. I am developing a system to analysis the rocking motion of a block subjected to an earthquake excitation. The state vector is y(t)={theta(t) , theta'(t)}. and the Time-derivative vector f(t) is y'(t)= {theta'(t) , p^2(sin(alpha*sgn[theta(t)]-th­eta(t))+u''/g*cos(alpha*sgn[th­eta(t)]-theta(t))]}. I have the values for p, alpha, u'' and g. But I need theta(t), and theta'(t). Can anyone help, I really need it!

[jakeblanchard]

@tomtomtramp

You can email me at blanchard "at" engr.wisc.edu

[dequinox]

Thanks for this, I couldn't figure out why my code wasn't working...everything looked good. Then I realized I forgot to define g. Dang I want those two hours of my life back! Lol

[smithforthphd]

thanks! I am a professor here at Oregon State. I am going to take this to the classroom!

[danielalonso23]

Thanks you very much dude¡¡¡¡¡¡, Greetings from Chile

[alpha001ful]

I tried to do the same simulation for a simple pendulum. Instead of y there , i had angle or variable called theta. Whenever i tried to run, Matlab always said "??? Input argument "theta" is undefined."........i have done exactly the same as here...