Computer Programming MC Practice

What does the following command yield?
>> clc

Clears the Command Window

What built-in function provides information about the data type?

whos

In the command window if we enter:
>> a=5
>> a=6
>> a

6

What does the following command yield?
> > clear

clears the workspace

MATLAB is a high-level language.

true

what is a variable?

A data container which can store a particular data.

The following is a series of commands entered in the Command Window:
>> pi = 2;
>> clear pi;
>> t = pi;
>> t

3.1416

What is the correct output for the following line of code:
-100 : 2 : -90

-100 -98 -96 -94 -92 -90

What is the correct output for the following line of code:

isprime(17)

1

What is the difference between the built-in functions sin and sind?

sin requires an argument in radians and sind requires an argument in degrees to output the expected answer

What is the correct output for the following line of code:
rad2deg(3.141)

180

What do the following lines of code output after the third line?
>> x = 'hello world'
>> x(6) = '&'
>> x

hello&world

Given the following lines of code, what is the index value for the third value of C (the third value in C is the number 3)?
>> x = [1 2 3;4 5 6;7 8 9];
>> y = [1,3,5,12,2,4];
>> [C index] = intersect(x,y);
>> C = 1
2
3
4
5

7

What would you expect the output of the variable cigarettes be after the third line of code?
>> cigarettes = [5 2 14 7 9 11];
>> cancer_prob = cigarettes 0.23 + 0.8
>> cigarettes(2) = 12;
>> cancer_prob = cigarettes 0.23 + 0.8
>> cigarettes(end+1) = 20;
>> cancer_prob = cigarettes * 0.23 + 0.8

[5 12 14 7 9 11]

How many data points does the following vector yield?
>> x = -pi:pi/4:pi

9

What goes in the dotted line to complete the code below?

load('knee_flexion.mat');
times = left_knee_flexion(:,1);
knee_angle = left_knee_flexion(:,2);
r = range(....................);
[peak, peak_index] = max(knee_angle);
peak_time = times(..........................);

(knee_angle) in line 4 and (peak_index) in line 6

What is the output after the second line of code is executed?
>> x = rand(10);
>> x(2:4 , :)

Outputs the values in the 2nd through 4th row all columns.

What would MATLAB output if you input the following command?
>> 1_x = 17

Error: The input character is not valid in MATLAB statements or expressions.

What are the 3 main areas covered in this introductory course?

MATLAB fundamentals, numerical techniques, programming structures

What does MATLAB stand for?

Matrix Laboratory

lower triangular

Which type of matrix has the following definition?

This type of matrix comes with all non-diagonal elements equal to zero, that is, only the diagonal entries of this square matrix can be non-zero, (aij=0;i≠j)

Diagonal matrix

tridiagonal

diagonally dominant

square, identity, diagonally dominant

[3; 12; 21; 12]

[1 0 0; 9 1 0; 0 0 4]

How many data points does the following vector yield?

>> x = -pi:pi/4:pi

9

What is the output after the second line of code is executed?

>> x = rand(10);

>> x(2:4 , :)

Outputs the values in the 2nd through 4th row all columns

%The output of the last line in the following program is

A= 10;

if (A >= 10)

B=5

else B= 6

end

B

5

The operator ~= stands for

Not equal to

Which of the following answers represents the matrix product of the following A*B?

row 1 (3 3) row 2 (5 7)

What is the value of y if x= 20 and the following commands are executed:

if x> 25;

y= 2;

elseif x> 21;

y=1;

else y=0;

end;

y

0

Your boss asks you to plot the following expression using MATLAB for t values between 1790 and 2000:

Choose the missing equation from the possible choices below to complete the following code:

t = 1790:10:2000;

P= ........................;

figure(15)

plot(t,P)

title('Section I: Problem 12')

197273000./(1+exp(-0.0313.*(t-1913.25)))

What is the output after running the following program:

A = 6;

B = 3;

if A > 5 | | B < 1

A = 20;

end

A

20

What is the output after running the following program:

A = 6;

B = 3;

if A > 5 && B < 1

A = 20;

end

A

6

Which of the following answers represents the inverse of matrix A?

row 1 (1 -2) row 2 (1.5 -0.5)

How many 'end' built-in functions need to be added to the end of the following program:

if BMI <= 18

disp(['Your BMI value is ', num2str(BMI), ' Kg/m^2 indicates that you are underweight']);

elseif BMI <= 25

disp(['Your BMI value is ', num2str(BMI), ' Kg/m^2 indicates that you have a normal weight']);

elseif BMI <= 30

disp(['Your BMI value is ', num2str(BMI), ' Kg/m^2 indicates that you are Overweight']);

else

disp(['Your BMI value is ', num2str(BMI), ' Kg/m^2 indicates that you are Over-overweight']);

1

Given the list of operator precedence below, what is the answer to the following: 

a = 3; b = 4; c = 5;

2*a - c + 4 : 6

5 6

What will be the output of the following code?

i = 5;

while i < 6

i = 5 + 1;

end

disp('This program ended!')

The program will run once displaying 'This program ended!'

"for loops" are the loops of choice when the programmer knows how many times a sequence of commands needs to be executed.

true

The output of the last line of this code is

for i=1:6

end

i

6

What is the output of the last line of this code:

scores =[ 4 3 5 1 3 ];

sum=0;

for i=1:length(scores);

sum=sum+scores(i);

end;

sum

16

Every " for " statement must be accompanied by an end statement

true

When does the while loop run its course and the program executes line 10?

1 clear; clc;

2 x = input('Enter x: ');

3 val = 1;

4 t = 1;

5 Percent_Rel_Error = 100;

6 while Percent_Rel_Error > 0.01

7 val = val + (x^t)/factorial(t);

8 Percent_Rel_Error = abs(val-exp(x))*100/exp(x);

9 t = t + 1;

10 end

When the condition for the while loop Percent Rel Error is equal to or less than 0.01

The following code is developed for a guessing game where the user is prompted to enter a positive number as a guess. Which change needs to be made to make sure the while loop is executed and the input prompt shows in the Command Window?

i = round(rand(1) * 9) % random integer between 0 and 9

guess = i;

while (guess ~= i)

guess = input('Guess a number:');

if (guess == i)

disp('Correct!');

else

disp('Wrong, try again ...');

end

end

Change the second line to: guess = -1;

"While loops" do not need to have an end statement.

false

Which answer completes line 4 in the code to make sure it works properly?

n = input('Enter a number you would like the factorial of: ');

1 f = n;

2 while n > 1

3 n = n-1;

4 f = ...........;

5 end

6 disp(['n! = ', num2str(f)])

f*n

The "tic" and "toc" built-in function allows the user to

Measures the elapsed time it takes to execute the code in between

To which line does the program go immediately after executing line 6?

1 total = 0;

2 while (true)

3 n = input('Enter number: ');

4 if (n < 0)

5 disp('Finished!');

6 break;

7 end

8 total = total + n;

9 end

10 disp(['Total = ' num2str(total)]);

Line 10

To which line does the program go immediately after executing line 6?

1 total = 0;

2 for i = 1:10

3 n = input('Enter number: ');

4 if (n < 0)

5 disp('Ignoring!');

6 continue;

7 end

8 total = total + n;

9 end

10 disp(['Total = ' num2str(total)]);

Line 2

What is the output of the following code?

asum = 0;

for a=1:3

asum = asum + a^2 + a;

end

asum

20

A function can have any number of input variables, any number of output variables, no input variables, no output variables.

true

What does nargin ~= 1 check for in the following code?

function [l,m] = compare_to_mean(x)

% usage: [l,m] = compare_to_mean(x)

% Input:

% x - A list of numbers

% Outputs: l - Number of values in x less than mean

% m - Number of values in x greater than mean

if nargin ~= 1

error('Compare to mean: %s', 'Expecting 1 argument')

end

m = mean(x);

less_array = find(x < m);

l = length(less_array);

more_array = find(x > m);

m = length(more_array);

end

Check if the user entered a number of variables other than 1 variable as the function input

A variable defined within a function is a considered a global variable.

false

A function that is written within a script m-file cannot be called outside of the file.

true

What is the output of ba(5) when you consider the two function below:

function m-file: foo.m

function out = foo(n)

out = 2 * n;

end

function m-file: ba.m

function m = ba(z)

m = 10 / foo(z)

end

1

To determine how efficient MATLAB code is, which one of the following would you use?

Use tic and toc commands

A pseudo code is

A mixture of non-specific computer language and English

Pseudo codes are written by

Humans for humans to read

flowline that connects symbols and indicates flow logic

terminal that represents the beginning or end of a task

input/output

processing for arithmetic and data manipulation operations

decision for logic of comparison operations

connector used to join different flowline

annotation that provides additional information about another flowchart symbol

used for loops/repetitions

Given the following flowchart, what would be the output?

b = 5; c = 20

Given the following flowchart, what would be the output?

a = 6, b = 5, c = 20

True error is defined as

True Value - Approximate Value

Approximate error is defined as

Present Approximation - Previous Approximation

Relative approximation error is defined as

Approximate Error/Present Approximation

The following gas stations were cited for irregular dispensation by the Department of Agriculture. Which one cheated you the most? (RELATIVE TRUE ERROR)

****************************************************************

Station Actual gas Dispensed Gas reading at pump

****************************************************************

Ser 9.90 10.00

Cit 19.90 20.00

Hus 29.80 30.00

She 29.95 30.00

***************************************************************

ser