Variable out_vec must be of size [1 3]. It is currently of size [1 20]. Check where the variable is assigned a value.

How can I reduce [1 20] size to a [1 3] size, without getting in the problem of needing only the number 1 10 and 20 in a vector row?

Answer 1

[KSSV]

x = 1:20 ;
idx = sort(randperm(length(x),3)) ;    % select randomly 
x(idx) 

ans = 1×3

3 6 8

[Raizel Lampert]

how does that get me the numbers 1 10 and 20 that are needed?

[KSSV]

x([1 10 20])