I'm totally new to Mathematica. I defined a simple matrix and I tried to query the elements of the matrix but I keep getting an error as shown in the figure attached. I don't know if I'm doing a mistake in the syntax or this is a bug. As a follow up to this question, another simple issue I'm facing is when I tried to evaluate some quantities I get a huge output with most of the terms multiplied by zero. Why is mathematica not making them zero, even when used with the commands `Simplify` or `FullSimplify`. Please let me know where I'm making the mistake. Thanks.

You are probably using the dot . as multiplication, but in WL it means scalar product of vectors. For example `{1, 1} . (0)` does not give zero. Plain multiplication is made with `*`

Yes that was the mistake I was making. Thanks for the help! It works now :)

Ah that makes sense, it is such a silly mistake on my part XD. Thanks for clearing that up. As to the follow-up I mean the results I show in the image attached There are terms here that are clearly zero since they are multiplied by zero, but Mathematica is not evaluating them. How do I fix this minor issue? Please help. Thanks.

Accessing matrix elements and evaluating terms multiplied by zero