Introductory Programming
Fall 2006

For today, you should have:

1) written mysum

2) prepared for a quiz


Today:

0) splitting sections

   Proposal: joint meeting Tuesday in auditorium.
             two sections on Thursday and Friday

	     Friday 9-10; what about Thursday?

1) mysum

2) program development process

3) Evaluation 3


For next time:

1) finish Eval 3 if you don't finish it today

2) work on the exercise below


mysum
-----

Write a function named mysum that takes a vector as an
input variable and that returns the sum of the elements
in the vector.

function s = mysum(V)
    total = 0;
    n = length(V);
    for i=1:n
        total = total + V(i);
    end
    s = total;
end


Program development
-------------------

Here is a sequence of steps to follow when you write programs:

1) start with a small, simple program that works

2) add a small number of lines of code

3) test the new code; get it working

4) go to step 2


For example, here is a series of steps for mysum:

1) write a function that always returns the value 17, and
   call your function from the interpreter

2) write a function that takes a vector as an input variable
   and returns the length of the vector

3) modify the previous function so it loops through the elements
   of the vector and prints them

4) add a variable named total that accumulates the sum of
   the values

5) assign the value of total to the output variable

6) add semi-colons to suppress unnecessary output


Exercise
--------

Write a function named "findit" that takes two input variables,
a vector and a target value.  Your function should search the
vector and return index of the first location where the target
value appears in the vector, or -1 if the target value does
not appear in the vector.