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Basic MATLAB MCQ

1. What is a reason to save a MAT-file using the -v7.3 flag?

To ensure backward compatibility

To avoid HDF5 overhead in MAT-file

To include a variable greater that 2GB

To use compression by default

Answer

Correct Answer: To include a variable greater that 2GB

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2. You wrote a new function named snap in an m-file and when you call it, you're not getting the output you expect. You previously wrote a different function named snap, which you think might also be on the search path. Which command can you use to see if the old snap function is being called?

Which

Who

Lookfor

What

Answer

Correct Answer: Which

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3. What do you call in the command window to see all the variables in the workspace and their classes?

Who

Vars

Whos

Who all

Answer

Correct Answer: Whos

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4. Which command will create a column vector with the values 7, 8, and 9?

C = [7,8,9]

C = [7: 8: 9]

C = [7; 8; 9]

C = [7 8 9]

Answer

Correct Answer: C = [7; 8; 9]

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5. Which statement reverses vector a? A = [ 1 2 3 4];

Reverse(a)

A(end:- 1:1)

Rev(a)

A(::-1)

Answer

Correct Answer: A(end:- 1:1)

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6. What is the size of b? a = [1 2 3]; b = repmat(a,2,3);

1x3

3x2

2x3

2x9

Answer

Correct Answer: 2x9

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7. Which statement will return all the odd numbers from 1 to 9?

2*[1:5]+1

1:2:9

Isodd(1:9)

1:odd:9

Answer

Correct Answer: 1:2:9

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8. You've just plotted some data and want to change the color behind the lines you've plotted to black. Which code block will accomplish this?

h_f = figure; set(h_f,'Color', [0 0 0]);

h_a = gca; set(h_a,'Color', [0 0 0]);

h_a = axes; set(h_a,'Color', [0 0 0]);

h_f = gcf; set(h_a,'Color', [0 0 0]);

Answer

Correct Answer: h_a = gca; set(h_a,'Color', [0 0 0]);

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9. For a 5 x 5 array, the two subscript index (4,2) indexes the same location as linear index ___.

Answer

Correct Answer: 9

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10. Which command will create a 10-element vector v with values from 1 to 10?

V = {1:10}

V = [1-10]

V = 1:10

V = (10)

Answer

Correct Answer: V = 1:10

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11. If you run this piece of code, you will get an error. Why? a = [0 1 2 3; 4 5 6 7]; a = a^2;

You are attempting to multiply a non-square matrix by itself, causing a dimension mismatch.

MATLAB does not allow you to square all the elements in the matrix in a single operation.

You must use the ** operator instead of the ^ operator.

You cannot square matrices that have a 0 as the first element.

Answer

Correct Answer: You are attempting to multiply a non-square matrix by itself, causing a dimension mismatch.

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12. Where in the UI can you see what variables have been created, their values, and their class?

Editor

Command window

Details

Workspace

Answer

Correct Answer: Workspace

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13. Which statement returns 1 (true)? a = 'stand' b = "stand"

a == b

Ischar(b)

Length(a) == length(b)

Class(a) == class(b)

Answer

Correct Answer: a == b

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14. What kind of files are stored with the .mat extension?

Figure files

Script files

Function files

Stored variable files

Answer

Correct Answer: Stored variable files

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15. Which is NOT a function that adds text to a plot?

Title

Text

Label

Legend

Answer

Correct Answer: Label

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16. Which statement creates a logical array that is 1 if the element in passwords contains a digit and 0 if it does not? Passwords = {'abcd' '1234' 'qwerty' 'love1'};

Contains(password, '\d')

~isempty(regexp(passwords, '\d'))

Cellfun(@(x) ~isempty(regexp(x, '\d')), passwords)

Regexp(passwords, '\d')

Answer

Correct Answer: Cellfun(@(x) ~isempty(regexp(x, '\d')), passwords)

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17. Which statement using logical indices will result in an error? A = 1:10;

B = a(a ~= 11)

B = a(a == 1)

B = a(a>6 && a<9)

B = a(a | 1)

Answer

Correct Answer: B = a(a>6 && a<9)

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18. Which statement is true about the sparse matrices?

You can use the sparse function to remove empty cells from cell array variables.

Sparse matrices always use less memory than their associated full matrices.

Mixtures of sparse and full matrices can be combined in all of MATLAB's built-in arithmetic operations.

The sparse function requires its input to be a full matrix with at least 50% zero elements.

Answer

Correct Answer: Sparse matrices always use less memory than their associated full matrices.

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19. Which statement returns a cell array of the strings containing 'burger' from menu? Menu = {'hot dog' 'corn dog' 'regular burger' 'cheeseburger' 'veggie burger'}

Menu{strfind(menu, 'burger')}

Menu(strfind(menu, 'burger'))

Menu{contains(menu, 'burger')}

Menu(contains(menu, 'burger'))

Answer

Correct Answer: Menu(contains(menu, 'burger'))

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20. You have loaded a dataset of people's heights into a 100 x 1 array called height. Which statement will return a 100 x 1 array, sim_height, with values from a normal distribution with the same mean and variance as your height data?

Sim_height = std(height) + mean(height) * randn(100, 1);

Sim_height = mean(height) + std(height) * randn(100, 1);

Sim_height = randn(std(height), mean(height), [100, 1]);

Sim_height = randn(mean(height), std(height), [100, 1]);

Answer

Correct Answer: Sim_height = mean(height) + std(height) * randn(100, 1);

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21. Which choice is the proper syntax to append a new elements a to the end of 1x 2 dimensional cell array C?

C = {C a};

C = cellcat(C a)

C = cat(2, {a}, C)

C{end+1}=a

Answer

Correct Answer: C{end+1}=a

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22. Which statement returns the roots for the polynomial x^2 + 2x - 4?

Poly([1 2 -4])

Solve(x^2 + 2x - 4 == 0)

Polyfit(x^2 + 2x - 4 == 0)

Roots([1 2 -4])

Answer

Correct Answer: Roots([1 2 -4])

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23. Which choice adds b to each row of a? a = ones(4, 4); b= [1 2 3 4];

A = a + reshape(b, 4, 1);

A = a + b';

A = a + repmat(b, 4, 1);

A = a + [b b b b];

Answer

Correct Answer: A = a + repmat(b, 4, 1);

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24. Which statement could create this cell array? c = {["hello world"]} {1×1 cell} {["goodbye"]} {1×3 double}

c = {"hello world" {"hello"} "goodbye" [1 2 ]};

c = {"hello world" {"hello"} "goodbye" {[1 2 3]}};

c = {"hello world" {"hello"} "goodbye" [1 2 3]};

c = {"hello world" {"hello" "hello"} "goodbye" {[1 2 3]}};

Answer

Correct Answer: c = {"hello world" {"hello"} "goodbye" [1 2 3]};

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25. Which function CANNOT be used to randomly sample data?

Datasample

Randi

Resample

Randperm

Answer

Correct Answer: Resample

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26. You have plotted values of cosine from -10 to 10 and want to change the x-axis tick marks to every pi, from -3pi to 3pi. Which statement will do that?

Xticks(-3pi:3.14:3pi)

Xticks(-3pi:pi:3pi)

Xticks(linespace(-3pi(), 3pi(), pi()))

Xticks(linespace(-3pi, 3pi, pi)

Answer

Correct Answer: Xticks(-3pi:pi:3pi)

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27. How do you access the value for the field name in structure S?

S['name']

S.name

S('name')

S{'name'}

Answer

Correct Answer: S.name

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28. You are in the middle of a long MATLAB session where you have performed many analyses and made many plots. You run the following commands, yet a figure window doesn't pop up on the top of your screen with your plot. What might be the issue? x = [-1:0.1:1]; y = X.^2; plot(x, y)

Your plot doesn't plot in a figure window because figure was not called immediately in advance.

Your plot syntax is incorrect.

Your plot is in a figure window that was already open, hidden behind other windows on your screen.

Your plot was saved to an image file but not displayed.

Answer

Correct Answer: Your plot is in a figure window that was already open, hidden behind other windows on your screen.

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29. For which of these arrays do mean, median, and mode return the same value?

[0 1 1 1 2]

[1 3 5 5 6]

[0 1 1 1 1]

[0 0 5 5 5]

Answer

Correct Answer: [0 1 1 1 2]

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30. Which function could you use for multiple linear regression?

Polyval

Regress

Solve

Polyfit

Answer

Correct Answer: Regress

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31. What is the . character NOT used for?

Structure field access

A decimal point

Cell array access

Element-wise operations

Answer

Correct Answer: Cell array access

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32. What is %% used for?

Argument placeholder

Block quotes

Code sections

Conversion specifier

Answer

Correct Answer: Code sections

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33. What does the Profiler track?

Execution time

Command history

Errors

The value of variables

Answer

Correct Answer: Execution time

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34. Based on the code below, c is the _ of a. a = rand(1, 11); b = sort(a); c = b(1, ceil(end/2));

Median

Mode

Mean

Margin

Answer

Correct Answer: Median

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35. From what distribution does the rand() function return value?

Normal

Poisson

Binomial

Uniform

Answer

Correct Answer: Uniform

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