# Seperately extract 11th and 21st element of matrix A

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fartyards on 28 Aug 2022
Commented: Star Strider on 28 Aug 2022
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.
dpb on 28 Aug 2022
<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

Star Strider on 28 Aug 2022
Moved: Matt J on 28 Aug 2022
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
.
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Star Strider on 28 Aug 2022
As always, my pleasure!