### 11.7.2 Rational function given by roots and poles

The fcoeff command finds a rational function given its roots and poles.

- fcoeff takes roots, a list consisting of the roots and poles of a rational function, each one followed by its multiplicity.
- fcoeff(roots) returns the rational function with the given roots and poles.

#### Example

fcoeff([1,2,0,3,2,-1])

| ⎛ ⎝ | x−1 | ⎞ ⎠ | 2 x3 | ⎛ ⎝ | x−2 | ⎞ ⎠ | −1