Thread: Finding roots with Newton's method

How can I find three roots of F(x)=cosx+0.2x with newton's method?
And,for all roots;I need take n(iteration number) ,but how can I identify iteration number?


thanks so much

Originally Posted by Mandelbrot

How can I find three roots of F(x)=cosx+0.2x with newton's method?
And,for all roots;I need take n(iteration number) ,but how can I identify iteration number?


thanks so much

You need to find starting points close to each root, they are close to . Then use standard Newtons method starting from each.

You don't normaly precompute how many itterations you need, but keep going untill is less than some preset tolerance.

CB

thank u CB,I will have to study with these roots now,then I'll think about iteration..

thank u so much