# Rational function given by roots and poles: fcoeff

### 5.33.2 Rational function given by roots and poles: fcoeff

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

- fcoeff takes one argument:
  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.

Input:

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

Output:

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