Solve Ordinary Differential Equations in Matlab

Here I describe how to solve a first order ordinary differential equation in Matlab using the ode45 routine. A high res version can be found at 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

[ReturnOfTheMack7]

the units aren't right... it's one thing to say it won't model reality and another to write an equation that doesn't make sense mathematically either.

[jakeblanchard]

@ReturnOfTheMack7

The units are fine. Of course, some of the numbers (like 4/15) are not dimensionless.

[jillukevin]

sir even if iam using the exact equation and coding as shown in this video it says input argument ' y ' is undefined . im new to this can u help me sir

[jakeblanchard]

@jillukevin

I would suggest you go to the link below and download the scripts. They should work for you. Sorry for the strange typing, but I've never figured out how to get a good link into a YouTube comment. I guess they are afraid of Spam, so they forbid the posting of links.

blanchard "dot" ep "dot" wisc "dot" edu/PublicMatlab/index.html#IV­P

[ukoba]

is it possible for me to download this movie? how should I go about this

[jakeblanchard]

@ukoba

I don't know of any way to do this directly. When I want to "download" a flash video, I use a screen capture utility. Lately I've been using TipCam, but there are others, including some web-based tools. Let me know if you need details.

[aztellez]

Perfect explanation, helped me solve a nasty ODE for a Heat Transfer final project. Life saver!

[azharshah316]

good explanation. Thanks

[ReturnOfTheMack7]

@jakeblanchard a number does not have units... no one should assume you have 'hidden' the correct units behind the fraction. you should leave it as a variable and explain the number and units [kg/m] as you do with m and g.

[uoweme5grand]

let`s say the function has consists of time being squared. so the dy/dt function has a t in it. would ode 45 still work?

[tomtomtramp]

Thanks for the vids! But 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). theta(t) is the rotation angle to time, t. Please help, I need it!

[lifeson32]

Clear and thorough. Thanks so much!