Let's break down and solve the questions on this sheet step by step:

1. What is the value of x after execution of the following code?

matlabCopy code
X = fliplr(sort([1 6 -1 2 -3 4]))

• sort([1 6 -1 2 -3 4]) sorts the array in ascending order:
  Result: [-3 -1 1 2 4 6]
• fliplr flips the array left to right (reverses the order):
  Result: [6 4 2 1 -1 -3]

Answer:
x = [6 4 2 1 -1 -3]

2. Single statement to extract the first column of matrix A.

If A is a matrix, to extract its first column in MATLAB:

matlabCopy code
A(:,1)

• : indicates all rows, and 1 indicates the first column.

Answer:
A(:,1)

3. Value of the code regarding the matrix A.

Given:
Matrix A: $A = \begin{bmatrix} 16 & 2 & 3 & 13 \\ 5 & 11 & 10 & 8 \end{bmatrix}$
Code:

matlabCopy code
A(mod(A,2)==0) = 0

• mod(A,2) returns a matrix where each element is the remainder when divided by 2. Even numbers yield 0, odd numbers yield 1.
• A(mod(A,2)==0) accesses all even numbers in A and sets them to 0.

Step-by-Step:

1. mod(A,2) result:
   $\begin{bmatrix} 0 & 0 & 1 & 1 \\ 1 & 1 & 0 & 0 \end{bmatrix}$
   • Even numbers: 16, 2, 10, 8
2. Replace even numbers with 0:
   $A = \begin{bmatrix} 0 & 0 & 3 & 13 \\ 5 & 11 & 0 & 0 \end{bmatrix}$

Answer:
$\begin{bmatrix} 0 & 0 & 3 & 13 \\ 5 & 11 & 0 & 0 \end{bmatrix}$

4. Which of the following means ≠ (not equal)?

• A) ~= → Correct
• B) <> → Incorrect (used in some other programming languages, not MATLAB)
• C) not = → Incorrect
• D) ~& → Incorrect

Answer:
A) ~=

5. Value of x after executing this code:

matlabCopy code
x = 0;
for n = 5:-1:-3
    if n > -2
        x = x + n;
    end
end

Step-by-Step Execution:

• Loop n = 5, 4, 3, 2, 1, 0, -1, -2, -3 (descending from 5 to -3).
• if n > -2: Condition is true for n = 5, 4, 3, 2, 1, 0, -1.
• Add n to x in each iteration.

Calculations:

• Initially x = 0.
• Add: 5 + 4 + 3 + 2 + 1 + 0 + (-1)
• Result: x = 14

Answer:
x = 14

6. Code to generate the matrix on the right from the matrix on the left.

The task is to convert a matrix such that all elements except the maximum in each row are set to 0.

Solution in MATLAB:

matlabCopy code
B = (A == max(A,[],2)).*A;

• max(A,[],2) computes the maximum value for each row.
• (A == max(...)) generates a logical matrix where only the maximum elements are 1.
• .*A multiplies element-wise, keeping only the maximum values and setting others to 0.

Answer:
B = (A == max(A,[],2)).*A;

Summary of Answers:

1. x = [6 4 2 1 -1 -3]
2. A(:,1)
3. $\begin{bmatrix} 0 & 0 & 3 & 13 \\ 5 & 11 & 0 & 0 \end{bmatrix}$
4. A) ~=
5. x = 14
6. B = (A == max(A,[],2)).*A;

Follow-up Questions:

1. How does the mod function work in MATLAB?
2. What is the difference between fliplr and flipud in MATLAB?
3. Explain how the max function works for rows and columns in MATLAB.
4. What does the .* operator do in MATLAB?
5. How can you extract the second row of a matrix in MATLAB?

Tip:

In MATLAB, mod(x,y) can help check divisibility, as mod(x,y) == 0 means x is divisible by y.