# Maple Unexpected result in Maple (fsolve returns negative value)

1. Jan 3, 2010

### EtherealMonkey

This is a problem that I am working on in Maple 12.

I have assigned the Differential Equation and the Initial Values for the two parts.

Then, I assigned the result to a variable before splitting off the two functions that return from dsolve.

Plotting the first function and the initial value allows me to see that the value should be somewhere around 13,000. But, fsolve is returning a value of -11400.

I have attached the Maple 12 worksheet and the original handout related to this question.

I would detail the problem, my attempt at solving it - etc; except that I do not really believe that would be as productive as having someone else look over the worksheet.

Also, this is the third attempt at entering the values in a 'new' worksheet. I have also opened the other attempted worksheets with Notepad2 (since it is an XML file) to see if there was some incorrect character or other invalid entry in the file. However, even starting with a new sheet is not returning a valid result (I do have another worksheet from when I took this course before where I received "13524.29951" as the result of fsolve at this point.)

If someone could enlighten me as to what in the world I am doing wrong (or if there is a way to limit the results returned by fsolve to a particular range (a>0?), then I would be most appreciative.

TIA,

E.

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2. Jan 5, 2010

### EtherealMonkey

Okay, here is a screen-shot of Maple with the problem loaded.

The issue that I am inquiring about occurs at Step #9 on the image below. As I stated in the first post, I am re-working this problem and cannot determine why I was able to find f(a)=13524.29951 when I originally worked the problem and now it is returning a negative value (restarting Maple, the machine, starting a new worksheet, etc...).

Note: I have updated Maple to the latest release on the maplesoft website (12.02).

---

Also, is there a way to limit the result from fsolve to a particular range? I have not found a way that is returning the value stated above {f(a)=13524.29951} and I presume that answer to be correct - since that is the approximate intersection of the plot shown in Step #8.

Thanks in Advance for any ideas,

E.

3. Jan 6, 2010

### mugaliens

I downloaded your image, but it's only marginally readable. Have you tried either PDF of JPG with 100%?

4. Jan 6, 2010

### EtherealMonkey

Sorry, I don't know what photobucket did to my png.

Here is the same image in PDF format (only marginally better - IMHO, but it is readable w/zoom )

#### Attached Files:

• ###### DioxinRemediation.Full.pdf
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268.8 KB
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