C# Newton Raphson Method

[Mulrian]

Just stumbled on a website providing a solution to the Newton Raphson method of solving polynomials.

Newton Raphson Website

However the particular example that they implement asks for a series of real coefficients which makes sense, but it also asks for 'imaginary coefficients', but i have no idea why it asks for them.

To try and solve an equation such as x^2 + 5x + 6, i put in 1,5,6 (at least i think this is correct) and because i dont know what to put for the imaginary coefficients i put the same. It gives me the correct answers of -2 and -3 along with some other weird answers.

Any ideas what this could be for and what i should put for them? I wont be dealing with complex numbers at all so can i just delete it? The rest of the code requires the list that it produces so i guess not.

However for other equations such as 2x^2 + 10x - 15 i put in 2,10,-15 for both and it gives me one correct answer but the other one doesnt work, is it me putting in the coefficients wrong or something to do with the code?

I am particulary interested in this code because of the way it solves for all roots instead of just the one that i am currently solving for in my implementation.

Thanks in advance

[mail]

First you should read up on how the newton method works - http://en.wikipedia.org/wiki/Newton%27s_method

Then you should read the article you linked because it clearly explains what they do.

[Mulrian]

I understand how the method works and the article says nothing about imaginary roots appart from in their implementation

On a completely different note i dont understand their method of finding other roots once one has been found.

In their example they use x^2 − 3x + 2 = 0 and get a first root of 2. I understand how to get to 1 * 2 + ( − 3) = − 1 by multiplying the coefficients etc but i get lost when it says how to display the results as 1 * x − 1 = 0. If i use this template all is good for other equations but i dont know how they actually got there. Plus is the same method applicable for cubic equations and if some what is the procedure?

Thanks for the reply