Seperately extract 11th and 21st element of matrix A

Hi,

I took Mathlab programming this semester and am still new to all of this.

So basically, I've been given this matrix A (5x5) as shown below.

A=[17 24 1 8 15; 23 5 7 14 16; 4 6 13 20 22; 10 12 19 21 3; 11 18 25 2 9]

So my question is, how do I extract 11th and 21st element of matrix A?

Thank you.

[Torsten]

How do you count the position ? Rowwise or columnwise ?

If Rowwise:

11th element: A(3,1), 21th element: A(5,1)

If Columnwise:

11th element: A(1,3), 21th element: A(1,5)

[N/A]

My question didn't state the position counting so I'm just gonna assume it's gonna start from rowwise (left to right). So I can only extract them one at a time instead of both simulatenously?

[Torsten]

A_11_and_21 = [A(3,1),A(5,1)]

[dpb]

<learn_matlab/array-indexing.html> is section in Getting Started doc about addressing arrays including this which is called linear indexing.

If in addition to the example you really were interested in traversing the array by row instead of column, then

M = reshape((1:25).', 5, [])*10;
M=M.';                              % transpose first
V = M([11 21])

V = 1×2

30 50

Answer 1

[Star Strider]

MATLAB generally uses columnwise linear indexing, so:

M = reshape((1:25).', 5, [])*10

M = 5×5

10 60 110 160 210 20 70 120 170 220 30 80 130 180 230 40 90 140 190 240 50 100 150 200 250

V = M([11 21])

V = 1×2

110 210

.

[N/A]

Got it, thanks so much for your help! :)

[Star Strider]

As always, my pleasure!