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- MATLAB indexing question 4 answers

Let my matrix be:

```
A =
[1,2,3;
4,5,6;
7,8,9];
```

I have to extract the values in (1,2), (2,3), (3,1). I tried the following:

```
c = [2,3,1]';
A(:, c)
```

but it gives a 3x3 matrix instead of 3x1.

How can I do it efficiently in matlab?

Answer:

The best way to extract arbitrary values from a matrix is to use linear indices.

You can use sub2ind

```
ind=sub2ind(size(A),[1 2 3], [2 3 1]);
val=A(ind);
```

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