I was wondering if someone might be able to explain what’s happening here. I am trying to create an array of values (A) and use a second array of values (B) to determine which values to read from A and return a vector (C) whose length is equal to that of B and has the values from A that correspond to the index values provided in B. Say I do the following: A = [0,1,2,3] B = [1,2,3,4,5,6,7,8,9] I’d expect: C = A[1,2,3,4,5,6,7,8,9] to return an out of dimension error – it does. But…If I instead do: C = A[B], I get: [1,2,3,3,3,3,3,3,3] Similarly, if I do: C = A[[1,2,3,4,5,6,7,8,9]], I again get: [1,2,3,3,3,3,3,3,3] and not the error that I would’ve expected to see. I’m obviously missing something here. I (wrongly?) thought the values in B would be used to index into A, so the value of 4 in B[3] should’ve been out of range for A. But it’s not. Any ideas what’s going on? I feel like I’m missing a subtlety in the syntax of what it means to nest square brackets. Alternatively, if there’s a better way to do this, I’m open to changing my approach.