E = 10 ^ (-3)
x=poly(0,"x")
f = x^4 + x^2 + 2 + 3*%i
x0 = 1
df = derivat(f)

x1 = x0 - horner(f,x0)/horner(df,x0)

it = 1
while abs(x1 - x0) > E
  x0 = x1
  x1 = x0 - horner(f,x0)/horner(df,x0)
  it = it + 1
end