RosettaCodeData/Task/Roots-of-a-function/Haskell/roots-of-a-function-3.hs

import Numeric.GSL.Polynomials
import Data.Complex

*Main> mapM_ print $ polySolve [0,2,-3,1]
(-5.421010862427522e-20) :+ 0.0
2.000000000000001 :+ 0.0
0.9999999999999996 :+ 0.0