Extract data from matrices and arrays using vectors of coordinates

I have a matrix and I want to use two vectors of row and column index coordinates in order to extract the elements from it. In particular, I can define a 3 x 3 matrix as

A = [1 2 3; 3 4 5; 8 9 10]

And I want to use two vectors to extract the elements (2,2), (3,1), (1,3). My intention is to do this using the vectors for each corrdinates. I have been trying to do it by writing

A([2 3 1], [2 1 3])

but of course this is not working. I believe that this is a basic sintax issue.

Thank you so much

Answer 1

[the cyclist]

Use the sub2ind function to convert the subscripts to a linear index into the matrix.

Using your example:

A = [1 2 3; 3 4 5; 8 9 10]

A = 3×3

1 2 3 3 4 5 8 9 10

linearIndex = sub2ind(size(A),[2 3 1], [2 1 3])

linearIndex = 1×3

5 3 7

A(linearIndex)

ans = 1×3

4 8 3

[Ariel Kessel Akerman]

Thank you!