Updated 4pm, Tues, 3/9

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pcode.zip has been updated to pcode_new.zip.
Nothing changes but just fix a bug in the Bisectionmethod.p .
The bug used to happen when input interval is [0, 2*3.4218] 
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1. Why I got an error when a3 runs exactmethod?

ans = 
exactmethod uses functions (i.e. sysm, etc.) of the symbolic math
toolbox, which not all versions of matlab have. That is why the error
may occurs. 

simple enough fix -- just comment out that instruction in the main
script (a3)  -- of course, you would need to replace a3.m for a3.p,
since you can't edit a p-file.  Since this step isn't required, not
much lost other than showing off some MATLAB coolness. 

2. What to do if Newton's Method gives negative answer? (How does
   program account for it?) 

ans =
The assignment leaves it open -- but does require that the program
handle it somehow. The easiest solution is prompting the user for a
new initial value. The better idea is to automate the choice of a new
initial value. Either is OK since we left it open.

3. Lots of questions in lecture about the Exact Method.

ans =
Yes, using FZERO or ROOTS does solve the problem, and we may even give
a few bonus points. But we are looking for use of the symbolic
toolbox. The problem is that not everyone has access. Since it's not
critical, we cannot provide much assistance other pointing you in that
direction.

4. Entering POS or NEG? (from Mikolaj in News)

ans =
You can use a little trick to do this. Create variables named "pos" and 
"neg", with specific values (for example pos=1 and neg=-1). Then, check 
if the user's input is "1" or "-1". When the user types in "pos", it 
gets translated into the value of the variable, so it gets interpreted 
correctly. The only catch is that if the user literally types in "1", it 
will also be accepted as "pos", but we won't take off any points for 
something like that.

5. Do I need to have MATLAB solve the derivative?

ans =
No. Solve by hand if you prefer and write your function (see Section
4.10).

6. Can I rewrite/write my own version of "readInt"?

ans =
Absolutely. In fact, people should be using readInt and other similar
I/O functions for better error-handling.

7. Can I rewrite any M-File you have provided?

ans =
No! Read the last sentence of the assignment.