Arrays1

What are matrices and arrays in MATLAB?

They are the basic building blocks in MATLAB

How are variables defined by default in MATLAB?

Every variable is defined as an array

What dimensions can an array have in MATLAB?

One-dimensional, two-dimensional, or higher

What is a one-dimensional array?

An array with only one row or one column

How can a one-dimensional array be created directly?

By listing elements separated by commas or spaces

How do you create a row vector using commas?

a = [1, 2, 4]

How do you create a row vector using spaces?

b = [4 5 6]

What type of arrays are row vectors?

One-dimensional arrays with one row

How can array size be checked?

Using the whos command

What does whos display?

Variable names, sizes, and data types

How do you create a column vector?

By separating elements with semicolons

Give an example of a column vector.

c = [7; 8; 9]

How can a row vector be converted into a column vector?

Using the transpose operator (')

What does a' do in MATLAB?

Converts a row vector to a column vector and vice versa

How can the colon operator convert vectors?

b(:) converts a row vector into a column vector

What is the colon syntax for creating arrays?

start:step:end

Give an example of colon syntax.

x = 0:2:10

What kind of array does colon syntax create?

An array with evenly spaced elements

Can colon syntax create decreasing arrays?

Yes

Give an example of a decreasing array.

y = 5:-2:0

What limitation does colon syntax have?

It does not explicitly specify the number of elements

What function creates linearly spaced arrays?

linspace

What is the syntax of linspace?

linspace(start, end, number of elements)

What is the default number of elements in linspace?

100

What does linspace distribute?

Elements linearly over an interval

What function creates logarithmically spaced arrays?

logspace

How are elements distributed in logspace?

Logarithmically over an interval

What is a two-dimensional array?

An array with multiple rows and columns

What is another name for a two-dimensional array?

A matrix

How do you directly create a matrix?

By separating rows with semicolons

Give an example of matrix creation.

A = [1 2 0; 4 5 6; 7 8 9]

How can arrays be concatenated vertically?

Using semicolons

What condition is required for vertical concatenation?

Arrays must have the same number of columns

How can arrays be concatenated horizontally?

Using spaces or commas

What does horizontal concatenation produce?

A longer array

What function creates an all-ones matrix?

ones

What does ones(3,2) create?

A 3×2 matrix of ones

What happens if ones has one argument?

A square matrix is created

What function creates an all-zero matrix?

zeros

Give an example of zeros usage.

zeros(4,2)

What function creates an identity matrix?

eye

What does eye(4) create?

A 4×4 identity matrix

Can eye create rectangular matrices?

Yes

Give an example of a rectangular identity matrix.

eye(4,3)

What function generates uniformly distributed random numbers?

rand

What is the range of rand values?

Between 0 and 1

What is the average value of rand?

0.5

How can you change the mean and range of rand?

By scaling and shifting the output

What function generates normally distributed random numbers?

randn

What is the mean of randn by default?

0

What is the standard deviation of randn by default?

1

How can you generate random matrices with a specific mean and standard deviation?

By scaling and shifting rand or randn

What does randn(size(A)) do?

Generates a random matrix with the same size as A

What is array addressing?

Accessing specific elements using indices

How do you access the third element of an array x?

x(3)

How do you access an element using row and column indices?

x(row, column)

What is the row and column structure of a row vector?

One row and multiple columns

What is the structure of a column vector?

Multiple rows and one column

What does the colon operator do in indexing?

Extracts a range of elements

How do you extract elements from index 2 to 5?

x(2:5)

How do you extract elements from an index to the end?

x(3:end)

How do you extract arbitrary elements?

Using an index array

How are submatrices created?

By specifying row and column ranges

How do you extract specific rows from a matrix?

Using row indices with colon for columns

How do you extract a full row?

D(3,:)

How do you extract a full column?

D(:,end)

How can a matrix be copied?

By simple assignment

How do you change a single matrix element?

Assign a new value using indices

How do you replace an entire row?

Assign a vector to that row

How do you delete a row?

Assign an empty array to that row

How do you delete a column?

Assign an empty array to that column

What does the length function return for an array?

The number of elements

What does length return for a matrix?

The largest dimension

What function returns matrix dimensions?

size

What does [r,c] = size(A) return?

Number of rows and columns

What does the max function do on an array?

Returns the maximum value

What does max return on a matrix by default?

Maximum of each column