The last two problems of exercise 11 use a maple program
to evaluate Fourier series.  It is important to do this,
because there could  be questions on the final that use the
intuition for understanding what Fouriers series are all about.
Understanding there is lots of software available for ODE and PDE
is probably just as important as any theoretical knowledge you
gained from the course (although the software is always easier to
use if you know a little theory).

To start the program, type  
         xmaple step.mws

Wait a bit.  The program takes some time to come up.  The program
can be modified in many ways (if you are curious and energetic).
This note is written only for the computer semi-literate.

The first function which has already been programed in, is the
function 1, made odd  (hence f(x)= -1 x < 0, f(x) = 1, x > 0). A
certain L length is chosen, which you can figure out from the
program, and the function is period of period 2L.

If the function 1 were made even, it would have a very dull cosine
series, namely just 1.

To make the program active, press return after every red command (which
yields a blue output).  If you change the red, the blue will change only
after you click on it.

To read details of any graph, put the cursor in the graph and click.
A new line appears at the top of the page, which will tell you 
coordinates (which is how you answer  what the maxima are).

To see the animation, and to rotate the 3-d graph, click in the graph
and use the line the appears at the top.  There are no questions about
this on the homework.