EXAM I - BME 201 - SPRING 2011
Instructions: You will have 55 minutes to complete the 3 questions below and the
Bonus. There are a total of 120 points available. Partial credit will be awarded if
your scratch work is organized neatly. Commenting your code is not required, but
will help us to award points when possible. You may use a calculator when
needed. Scratch paper is available at the front of class. Good luck!
Question 1. (30 pts):
k = 2;
A = [12 6 8 4; 3 5 1 13; 4 0 7 2]’;
a. Write out the matrix A as specified above? (5 pts.)
b. Write Matlab code to extract the third column of the matrix A and set it equal to a
variable called third_column. What is the value of third_column ? (5 pts.)
c. Write Matlab code to extract values from A to create a column vector called
diag_vec that is comprised of the elements along a diagonal spanning from the
bottom left element of A to the (2,3) element of A. What is the value of diag_vec
? (5 pts.)
d. Write Matlab code to extract the first three elements of the second column of A
and store them in a column vector called short_col. What is the value of short_col
? (5 pts.)
e. What will the Matlab command mult1 = short_col .* [ 2; 4; 6;] set mult1 equal to?
(5 pts.)
f. What will the Matlab command mult2 = A(1, :)* A(k-1:k+1,3) set mult2 equal to?
(5 pts.)
Question 2 (40 pts.):
updown = [2, 1, 5, 6, 7];
time = [1, 2, 3, 4, 5];
a. Write Matlab code using a while loop to determine endtime, the value of the array
time when the value of the array updown is both above 5 and increasing. Be sure
your code is flexible enough to do this for updown arrays of any length (20 pts).
b. Track the values in your code to verify it returns the correct answer (20 pts).
