Question

I am doing the newton's method homework. are we supposed to be able to find non-real roots?

Answer 1

Newton's method won't find complex roots, unless by some strange coincidence.
Think about it this way, the derivative of a polynomial is a polynomial. There is no way for a polynomial divided by a polynomial to return a complex number.

Answer 2

Thanks. I am just checking. Just spent an hour trying to figure out why my code wouldn't find the roots when I realized there were no real ones (I put in x^2+2x+3).

Answer 3

I'm guessing you will have a max number of iterations to prevent infinite loops.

Answer 4

I tried a few iterations and it looked like it was doing what it was supposed to. Then I put a while f(x)>epsilon loop that kept going so I tried to trouble shoot with a for loop with ever growing repetitions (first 10 then 100 then 1000 and so on) but it never seemed to getting closer to one value. I did some research and most 2 degree polynomials got a close root in less than 10 iterations. Oh well...