Question

Given the array A=[2797;3156;8125]. Explain the results of the following commands:

i. A'
ii. A(:,[1 4])
iii. A([2 3],[3 1])

Answer 1

i. The result of A' is a transpose of the array A, which is
`[2797; 3156; 8125].`

ii. The result of
`A(:,[1 4])` is an array containing the first and fourth elements of each column of
`A, i.e., [2797; 8125].`

iii. The result of
`A([2 3],[3 1])` is a subarray that includes the elements in the 2nd and 3rd rows and the 3rd and 1st columns of A, resulting in
`[8125; 3156].`

Step-by-step explanation:

i. The transpose of an array is obtained by switching its rows and columns. In this case, A has one column and three rows, so the transpose is a
`3x1` array, which remains
`[2797; 3156; 8125].`

ii.
`A(:,[1 4])` selects all rows and only the columns specified in the index vector [1 4]. This results in a new array consisting of the 1st and 4th elements of each column of A, which are
`[2797; 8125].`

iii.
`A([2 3],[3 1])` selects the 2nd and 3rd rows from A and, within those rows, the 3rd and 1st columns. The resulting subarray is
`[8125; 3156].`

In summary, the explanations detail the outcomes of each command in the given context.