# Substituting variables in instances of elements of SymmetricFunctions of polynomial rings

I am working with

```
R.<q,t> = PolynomialRing(QQ)
```

```
Q = R.fraction_field()
```

```
Sym = SymmetricFunctions(Q)
```

following which I declare `Ht = Sym.macdonald().Ht()`

. I would now like to evaluate `Ht`

for different relations between `q`

, `t`

. As an example, I would like to be able to compute `Ht[2,1,1]`

with the substitution `q -> q`

and `t -> 1`

.

I mean being able to evaluate something like

`Ht[2,1,1]`

but with the substitution`q=t`

or`t=1`

.