class MATH is
  nthroot(n:INT, a:FLT):FLT
    pre n > 0
  is
    x0 ::= a / n.flt;
    m  ::= n - 1;
    loop
      x1 ::= (m.flt * x0 + a/(x0^(m.flt))) / n.flt;
      if (x1 - x0).abs < (x0 * 1.0e-9).abs then
        return x1;
      end;
      x0 := x1;
    end;
  end;

end;