Penn State University Department of Mathematics Eberly College of Science
How to use Direction fields 4

Here are instructions how to use Direction fields 4. Let me solve as an example problem 1 from section 1.1 on p.7.
1. Go here.
2. You will see there a webpage that looks like this
3. Problem 1 asks to plot y'= 3 - 2y. First we need to convert this expression so that the applet will understand us. You should write 3-2*y (star mean multiply, see the link View Instructions on using the Applet for other formulas). Then we type in the slot eqn #1 dy/dx = the formula:
and then press "Submit All" button
4. At this point you will have something like this. Play with the parameters Min. x Max x. Min. y Max y Num of segs in order to get a better picture. See my example
5. Finally, in order to see what happens as t -> infinity, click on a few points on the y-axis. This will draw trajectories, see my example In our particular case everything goes to y=1.5