PRACTICE EXAM I - BME 201 - SPRING 2011
Note: Please bring a calculator to the exam. You will need it and I will not have
extras.
Question 1 (40 pts):
A = [1,6,8; 3,5,1; 4,7,2];
a. Write Matlab code to extract the third column of the matrix A and set it equal to a
variable called third_column. (8 pts.)
b. Write Matlab code to extract values from A to create a column vector called
diag_vec that is comprised of the elements along the diagonal spanning from top
left to bottom right of A. (8 pts.)
c. What will the Matlab command ewise = A(:,1).* A(:,3) set ewise equal to? (8 pts.)
d. What will the Matlab command not_ewise = A(1, :)* A(:,3) set not_ewise equal
to? (8 pts.)
e. Write Matlab code to extract the last two elements of the third row of A and store
them in a row vector called row_vec (8 pts.)
Question 2 (30 pts):
imagedata = [8,20,6,11,3];
a. Write Matlab code using a for loop to return the number of elements in the array
imagedata that are between the values 5 and 18. The code should be general
enough to handle data arrays of different lengths (15 pts).
b. Track the values in your code to verify that it returns the correct answer (15 pts).
Question 3 (30 pts.):
updown = [2, 4, 6, 8, 7, 5, 4];
time = [1, 2, 3, 4, 5, 6, 7];
a. Write Matlab code using a while loop to determine the time when the value of the
array updown first stops increasing (15 pts).
b. Track the values in your code to verify it returns the correct answer (15 pts).
BONUS (20 pts.):
For the following code:
x=[2,4,7,9];
y=3;
z=[4 5 2 6 ; 3 7 2 4 ; 5 9 8 4 ; 1 1 6 3 ] ;
N=length(z(:,1));
for k=1:length(x) ;
for n=1:N
ww = z(n,k)*y + x(k)
W(k,n) = ww;
