[wp34s] Poly root finders?

[BarryMead]

(12-03-2015 06:22 PM)emece67 Wrote:  in my case with polinomial $$z^2+1=0$$ giving a double root at z = 0, which is obviously wrong.

The REAL component of both roots IS ZERO. Either you are not reading the answers correctly, or the root solver you picked isn't handling complex answers very well.
Since this particular equation is only of degree 2 you could always solve it with the SLVQ funciton. Put 1 in Z, 0 in Y and 1 in X Representing the a, b and c coefficients of the quadratic equation, and press X.FCN SLVQ.

Immediately after the SLVQ step, the first answer appears in the display. (0 + i1)
When the answer is complex, the manual says the second answer is the complex conjugate of the first, so press CPX X.FCN CONJ then the second answer (0 - i1) appears in the display.

The roots of this equation are (0 + i1) and (0 - i1)

I hope this was helpful, Barry