1 | initial version |

Because of Sage prepersing, when you define `f(x)=...`

you define a symbolic function, where the `x`

is a symbol, not an element of the ring you just defined, see

```
sage: parent(f)
Callable function ring with argument x
```

If you want to stay in `R`

, you should define `f`

as follows:

```
sage: R = ZZ['x']
....: x = R.gen()
sage: f = 122313*x^23 + 445*x^12 + 2013*x + 2345
sage: parent(f)
Univariate Polynomial Ring in x over Integer Ring
```

Then you can define the derivative of `f`

directly as:

```
sage: h = f.derivative()
sage: h
2813199*x^22 + 5340*x^11 + 2013
```

and evauate it:

```
sage: h(5)
6707189083360107423888
```

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