Question: Imagine I have many expression of the form `\phi_{i0}^A`, `\phi_{i1}^A`, etc.

I want to create a macro such that `^A` is appended automatically and I don't have to type it in, e.g. `\phispecial_{i0}` would produce the same result.

So far I've tried `\DeclareMathOperator{\phispecial}*{\phi^A}` but that produces misaligned results. Do I have to use `\newcommand` instead?

Answer: 
Here there is no need for `\DeclareMathOperator` as this is probably not somethig that needs to behave like `\log` and friends. So

```
\newcommand\phiA{\phi^A}

```

is enough since `A_b^c = A^c_b`
Please define like below

```
\newcommand\phiA[1][A]{\phi^A}

```

and try