MATLAB Part-II

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MATLAB Part-II

You have a matrix data in which each column is mono audio recording from a room in your house. You've noticed that each column has a very different mean and when you plot them all on the same graph, the spread across the y axis make it impossible to see anything. You want to subtract the mean from each column. Which code block will accomplish this? *

1 point

data_nomean = data - repmat(median(data), size(data, 1), 1);

data_nomean = bsxfun(@minus, data, mean(data));

Option 3

data_nomean = zscore(data');

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? *

1 point

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]);

Which choice adds b to each row of a? *

1 point

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

a = a + b';

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

a = a + [b b b b];

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

1 point

poly([1 2 -4])

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

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

roots([1 2 -4])

What is the set of possible values that a may contain? *

1 point

3, 4, 5, 6, 7, 8, 9, 10, 11, 12

1, 2, 12

2, 11, 12

1, 12

Which statement creates this structure? *

1 point

dog = struct('name', 'Bindy'; 'breed', 'border collie'; 'weight', 32);

Option 2

Option 3

Option 4

Which code block results in an array b containing the mean values of each array within C? *

1 point

Option 1

b = cellfun(@mean, C);

Option 3

b = cellfun(@(m) mean(m(:)), C)

Which statement turns menu into the variable menu_string below? *

1 point

menu_string = cell2mat(join(menu, newline))

menu_string = cell2mat(join(menu, '\n'))

menu_string = join(menu, newline)

menu_string = cell2mat(pad(menu))

Which statement is true about the sparse matrices? *

1 point

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.

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

1 point

C = {C a};

C = cellcat(C a)

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

C{end+1}=a

Which choice will NOT give you a 5 x 5 identity matrix? *

1 point

Option 1

diag(ones(5, 1))

identity(5)

eye(5)

Which statement creates a logical array that is 1 if the element in passwords contains a digit and 0 if it does not? *

1 point

contains(password, '\d')

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

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

regexp(passwords, '\d')

Which statement returns a cell array of the strings containing 'burger' from menu? *

1 point

menu{strfind(menu, 'burger')}

menu(strfind(menu, 'burger'))

menu{contains(menu, 'burger')}

menu(contains(menu, 'burger'))

Which is NOT a function that adds text to a plot? *

1 point

title

text

label

legend

Which statement using logical indices will result in an error? *

1 point

b = a(a ~= 11)

b = a(a == 1)

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

b = a(a | 1)

Which statement could create this cell array? *

1 point

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]}};

Which choice replaces all as with os? *

1 point

Option 1

Option 2

Option 3

Option 4

Which code snippet sets a new random seed based on the current time and saves the current settings of the random number generator? *

1 point

rng_settings_curr = rng('shuffle');

Option 2

rng_settings_curr = rand('shuffle');

Option 4

Which choice has a different final result in f10 than the other three? *

1 point

Option 1

f10 = factorial(10)

Option 3

f10 = prod(1:10)

my_func is a function as follows. What is the value of a at the end of the code beneath? *

1 point

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