FREE MATLAB Programming and Scripting Questions and Answers

Question 1

What is the final value of the variable `total` after the following MATLAB code is executed?

```matlab
total = 0;
data = [10, -5, 20, 0, -15, 30];
for k = 1:length(data)
    if data(k) < 0
        continue;
    end
    total = total + data(k);
end
disp(total);
```

Accepted Answer

60

Answer

40

Answer

75

Answer

An error will occur because `continue` is not a valid command.

Question 2

Which of the following lines of code correctly defines an anonymous function named `vol` that calculates the volume of a sphere (4/3 * pi * r^3) and then correctly calls it for a radius of 5?

Accepted Answer

vol = @(r) 4/3*pi*r^3; result = vol(5);

Answer

vol = function(r) 4/3*pi*r^3; result = vol(5);

Answer

function vol(r) = 4/3*pi*r^3; result = vol(5);

Answer

vol = @(r) 4/3*pi*r^3; result = @vol(5);

Question 3

A programmer needs to store a character vector 'Test', a numeric vector `[1 2 3]`, and a 2x2 matrix `magic(2)` together in a single 1x3 container variable. Which data structure is most appropriate, and how is the numeric vector `[1 2 3]` correctly accessed from the container named `C`?

Accepted Answer

A cell array; accessed with `C{2}`

Answer

A structure; accessed with `C.data2`

Answer

A standard matrix; accessed with `C(1,2)`

Answer

A table; accessed with `C(:,2)`

Question 4

Which of the following best describes the primary purpose of a `try-catch` block in MATLAB programming?

Accepted Answer

To allow code that might produce a runtime error to execute, and to run a separate block of code if an error occurs, preventing the program from crashing.

Answer

To validate user input from the `input` function by attempting different data type conversions.

Answer

To preallocate memory for an array to improve performance before entering a loop.

Answer

To define a conditional block of code that runs only if a specific logical variable is true.

Question 5

Why is preallocating an array before it is populated inside a `for` loop a recommended best practice in MATLAB for improving performance?

Accepted Answer

It prevents MATLAB from having to repeatedly find new contiguous blocks of memory and copy all existing data as the array grows within the loop.

Answer

It ensures the array elements are all integers, which are processed faster than floating-point numbers.

Answer

It is a required syntax for using the `parfor` (Parallel Computing Toolbox) construct.

Answer

It automatically initializes all array elements to a non-zero value, which prevents `NaN` (Not-a-Number) errors during calculations.

Question 6

Given the following string array: 
`fileNames = ["data_01.csv", "notes.txt", "data_02.csv", "backup_data.zip"]`

Which command will return a logical array `[1 0 1 1]` indicating which elements contain the substring "data"?

Accepted Answer

`contains(fileNames, "data")`

Answer

`find(fileNames, "data")`

Answer

`strcmp(fileNames, "data")`

Answer

`ischar(fileNames, "data")`

What is the final value of the variable `total` after the following MATLAB code is executed?```matlabtotal = 0;data = [10, -5, 20, 0, -15, 30];for k = 1:length(data) if data(k) < 0 continue; end total = total + data(k);enddisp(total);```

What is the final value of the variable `total` after the following MATLAB code is executed?
```matlab
total = 0;
data = [10, -5, 20, 0, -15, 30];
for k = 1:length(data)
if data(k) < 0
continue;
end
total = total + data(k);
end
disp(total);
```