## Homework 2, due January 31, 2007.

Due Wednesday, January 31, 2007.
goodwine
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### Homework 2, due January 31, 2007.

Unless otherwise indicated, all problems are from the course text, Elementary Differential Equations and Boundary Value Problems, by Boyce and DiPrima, 8th Edition.

Reading sections 7.1 through 7.5 will be helpful to fill in a few details that were not covered in lecture.
1. Section 7.2, numbers 4, 15 and 23.
2. Section 7.5, numbers 4, 6 and 16 (by hand) and 13 (may use computer for computations, but submit printed computer work).
3. Determine the general solution to
Determine the solution if
and
Bill Goodwine, 376 Fitzpatrick
nfraser

### Section 7.5, numbers 4, 6

Is there an easy way to plot the direction field in MATLAB for numbers 4 and 6 in section 7.5?
goodwine
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Joined: Tue Aug 24, 2004 4:54 pm
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### Re: Section 7.5, numbers 4, 6

nfraser wrote:Is there an easy way to plot the direction field in MATLAB for numbers 4 and 6 in section 7.5?
There is but I don't know off hand. Maybe someone else can post the answer. If not I'll try to dig it out before the end of today (Monday).
Bill Goodwine, 376 Fitzpatrick
goodwine
Posts: 1596
Joined: Tue Aug 24, 2004 4:54 pm
Location: 376 Fitzpatrick
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### Re: Section 7.5, numbers 4, 6

goodwine wrote:
nfraser wrote:Is there an easy way to plot the direction field in MATLAB for numbers 4 and 6 in section 7.5?
There is but I don't know off hand. Maybe someone else can post the answer. If not I'll try to dig it out before the end of today (Monday).
I would suggest googling "matlab plot vector field".
Bill Goodwine, 376 Fitzpatrick
awulz

### Plotting Direction Fields

Here is a link that is pretty easy to follow:

http://www.wam.umd.edu/~petersd/246/matlabode2.html

Just scroll down the page to:
"Vector fields for autonomous systems of two first order ODEs."
Note: You'll need to save the .m file they have listed on the website to use with Matlab.

Alex
gsuarez1

### HW 2 graph

Do we have to use MATLAB? Can we use another computer program like Mathematica for example?
goodwine
Posts: 1596
Joined: Tue Aug 24, 2004 4:54 pm
Location: 376 Fitzpatrick
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### Re: HW 2 graph

gsuarez1 wrote:Do we have to use MATLAB? Can we use another computer program like Mathematica for example?
I assume you are referring to plotting the vector fields. For those you may use whatever you want, including Mathematica or even plotting it by hand.
Bill Goodwine, 376 Fitzpatrick
Euler

### direction field

Hi. I think pplane is the easiest way to do it. There is a JAVA version now, or you can still download the MATLAB. I think this is the correct URL http://math.rice.edu/~dfield/dfpp.html.

Just make xdot, xdot and ydot, in place of x1dot and x2dot. Then make x1, x, and x2, y.

Then it's really easy to enter and plot right away.

You can click on the window to get neat traces between the arrows.

I want to know how to do it in Mathematica. Did anybody figure that out?
goodwine