* Scheme expression

       Math expr.               Scheme expr.
       ----------               ------------
       x + y                    (+ x y)
       x * y                    (* x y)
       x + y * z                (+ x (* y z))

       - In general, a function f(x,y,z) is handled in Scheme with (f x y z)

       - In Scheme, containing single operations in parentheses remove
         ambiguity in evaluation order (i.e. PEMDAS rule is irrelevant)

       - In Scheme, there are 3 general categories of values: numbers,
         symbolic values, and list/trees/structures.  These will be
         discussed in detail as they come up.


* Practical DrScheme Information

       - There are two windows in the interface: definitions and
         interactions (You can hide either.)

         Use the interactions window to explore language and test things
         out

         Use the definitions window to define functions.  After this is
         done (and the execute command is run), you can try out the
         function in the interactions window.

       - Find out info about built-in functions from the manual
         accessible from the help menu.


* Demo: A recursive exponentiation function, using recursion. (See demo pages.)

       - Note the syntax form for the conditional expression.  This
         deviates from the standard expression form.	

       - Note that a negative exponent causes an infinite recursion.
         This arises from a lack of negative value handling in the
         conditional. 


* Programmers are often interested with the "rough" number of steps an
  algorithm takes.  "Rough" typically implies the dependence on an
  iteration index n, ignoring constant scale factors and additions
  (i.e. 100*n + 20 is roughly n)