I asked a question about ua(x) just now.
Then I realized I have no idea how to read aloud the symbol.
Usually I read aloud X1 as "X one". Should I read aloud ua(x) as "u a of x"?
I would pronounce this:
as f of x.
And I would pronounce this:
as u sub a.
Therefore, I would pronounce your expression as: u sub a of x.
Note: This assumes that ua is a function. If ua was a variable and not a function, then I suppose this could be a multiplication expression instead. In that case, I would say: u sub a times x
Here u refers to an object with a dependance to another object a.
When a is an integer, we commonly say that u is a sequence.
More generally, if a is a complex number, we can say that u is a function of a (just like in the idea that u is function of a, I.E. it depends on a ).
So simply, just as you read "f(x)", f of x, i'd say "ua(x)" u of a, because you could also write
ua(x) = u(a)(x)