x = Array[a, {4, 3, 5}];

i = {1, 2, 3};

Element to be modified

x[[Sequence @@ i]]

a[1, 2, 3]

Change element

x[[Sequence @@ i]] += 1

1 + a[1, 2, 3]

Verifying that array was modified

x[[Sequence @@ i]]

1 + a[1, 2, 3]


Bob Hanlon


On Wed, Jul 4, 2012 at 3:32 AM,  <samid.hoda@gmail.com> wrote:
> Hi,
>
> I want to edit an element whose position is specified by an arbitrary list that is a result of a computation (the list is not of fixed length). Something like
>
> i = {1,2,3}
> Extract[X,i]+=1
>
> except that Extract passes X by value instead of by reference. Anyone have any ideas?
>
> Thanks,
> Sam
>