Department of Computer Science
Computer Science 101: Mid Term Exam I (60 minutes)
Name: NetID:
Lab Section: Date: 9/30/10
No questions
will be answered during this examination.
If you do not understand a question, read it again. If you still do not understand it, make reasonable assumptions and write them
down. (Points will be deducted if unreasonable assumptions are made.)
DO NOT CHEAT: Cheating includes not only copying from another person but
also allowing someone to copy from you.
Anyone who copies or allows someone to copy will receive a score of
zero. So be defensive and protect your
work.
This examination contains 8 pages including this page. Check that your copy is complete, and ask for a replacement if it is not. Do all your work on these pages. For your own protection, in case pages come apart, write your NetID at the TOP of each page before beginning work.
Do not forget to sign the attendance list. If your exam is
misplaced and you did not sign the attendance list then you will receive a zero
score for the exam.
You may not use any electronic devices, book, notes or other
references during this examination.
DO NOT WRITE IN THIS SPACE
Section |
Possible Score |
Deduction |
Grader |
|
6 |
|
|
|
|
2 |
6 |
|
|
|
3 |
5 |
|
|
|
4 |
5 |
|
|
|
5 |
6 |
|
|
|
6 |
7 |
|
|
|
7 |
7 |
|
|
|
8 |
9 |
|
|
|
9 |
7 |
|
|
|
10 |
8 |
|
|
|
11 |
8 |
|
|
|
12 |
9 |
|
|
|
13 |
8 |
|
|
|
14 |
5 |
|
|
|
15 |
6 |
|
|
|
16 |
9 |
|
|
|
17 |
8 |
|
|
|
18 |
6 |
|
|
|
Total |
125 |
|
|
|
|
|
Exam Scoreà |
|
A
1. Write the results Matlab
returns for the following commands typed in the Matlab command window.
>>
clear
>> x=4;
>> who
_____________________________________________________
2.
Write the results
Matlab returns for the following commands typed in the Matlab command window.
a) >> z = 0:0.3:1
z =
_____________________________________________________
b) >> w = linspace(3,8,2)
w =
_______________________________
3.
Write the results Matlab returns for the following commands
typed in the Matlab command window.
>> x = [1 2 3 4];
>> y = [5 6 7 8];
>> z = [x(end:-1:end-2),y(2:3)]
z =
_____________________________________________________
4. If X = [ 1 3 5 7 9 11];
Write a Matlab command to display:
flipX =
9
7 5 3
Your answer must use X or you will not receive any
credit.
>> flipX = ___________________________________________________
5.
Given the code for the
function named rolldice as shown below:
function
c = rolldice(n)
% function c =
rolldice(n)
% rolldice:
simulate the roll of a six sided die.
% returns a random
integer between 1 and 6 inclusive.
c =
ceil(6*rand(1,n));
How
would you call the rolldice function to simulate 4 die rolls?
>>
_____________________________________________________
6.
Write the results Matlab
returns when you type the following commands in the command window.
a)
>> x = ceil([1.9
3.4 -4.9 -5.3])
x =
____________________________________________________________
b)
>> y = diff([2 4 -5 -6])
y =
____________________________________________________________
7. Given A=[1; 2], B=[3,4], circle the result Matlab will return when you type the following
command in the Matlab command window. There is only one correct answer.
>>
A*B
a) ERROR
b) 1
c) 2 2
d) 3 4
6 8
8. Complete the Matlab code below by filling in the blanks to solve the following linear system of
equations:
100x
+ y + z = 1
x +
20y + z = 20
x + y
+ 50z = 10
where x,y and z are variables. We consider the problem mathematically as A*b = c .
>>
A = ____________________________________________________;
>>
c = ____________________________________________________;
>>
b = ____________________________________________________;
9. Given
that Mat =
2
4 6
3 10
14
5
7 10
circle the result Matlab will return for the following Matlab command typed in command window.
There is only one correct answer.
>>
Mat(1,:) + Mat(:,2)'
a) 6
14 13
b) ERROR
c) 5
14 20
d) 6
13 12
10. Given
that A = [2 4 6] and B=3, which
Matlab expression below would you fill in the blank to give you the column vector shown below?
>> ___________________
ans=
6
12
18
Please circle each correct answer. (Note that there may be more than one correct answer.)
a) A'*B
b) A'.*B
c) A*B'
d) (A*B)'
11. Fill
the the blanks below to plot function: f(x)
= sin2(x) between -π
and π inclusive. Note that the function is fplot and NOT
the plot function.
>> fplot( ___________________, _____________________);
12. Plot the 3-D surface described by the equation, z
= x + y. In the region in
the x-y plane from x = -4 to 4
and y
= -5 to 5
>> x = linspace( _________________, _________________,
100);
>> y = linspace( _________________, _________________, 100); >>
x = linspace(___, ___, 11);
>>
y = linspace(___, 5, 9);
>>
[xMAT, yMAT] = meshgrid(x, y);
>> zMAT = ______________________________________________ ;
>> surf(xMAT, ________________________, ________________________)
13. Given the code for the
function named func
as shown below,
function out = func(x, y)
out = x
+ y;
circle each correct way to call the function named func. By correct way we mean any
way that
does not
produce a Matlab ERROR. (Note
that there may be more than one correct answer.)
a)
>> result = func(1)
b) >> result = func([1 2],
[3 4])
c) >> func(2, 1)
d)
>> func(1+2, 3/4)
14. There
is a symbol in Matlab such that when it is typed within a function, all the
following text on that line is ignored by Matlab. This line is called a
comment. Circle the answer choice for the symbol that will create a comment in
Matlab. There is only one correct answer.
a)
#
b) %
c) “
d) $
15. Match
the following incomplete lines of code with the appropriate function name that
would NOT produce an error when
typed in the Matlab command window. You may assume that the sin and deriv
functions are previously declared functions and work without error.
a) >>_______(@sin, 0, pi) 1) quadl
b) >>_______([-1 0 1], [1 0 1]) 2)
ode45
c) >>_______(@deriv, [0, 500], 0) 3) trapz
16. Complete the function named find_x by filling the in blank. The function find_x has two input arguments, x and y that will hold vectors of equal length. The function find_x returns the x value(s) whose position equals the maximum value of y.
For example, given x and y below,
>> y = [ 1 0 5 0 3 0 4 0 5 0 ];
>> x = [ .1 .2
.3 .4 .5
.6 .7 .8
.9 1.0 ];
then calling the function find_x produces the following result.
>> result = find_x(x,y)
result =
0.5
Of course your
code should work correctly for any choice of vectors x and y of
equal length.
function result = find_x(x,y)
result = ____________________________________
17. Given the vector p below,
>> p = [ 2 3 4 5 2 4 2 ];
write the output produced by typing the following Matlab command in the command window. If the command produces an error write ERROR.
>> x = p( p ~= 2 )
x =
___________________________________
18. Given
the vectors p and y below,
>>
p = [ 1
0 0 0
1 1 1 ]
>> y = [ 0 1
1 1 0
0 0 ]
write the output produced by typing the following Matlab command in the command window.
If the command produces an error write ERROR.
>>
x = y(p)
x
= ____________________________________________