Newton-Raphson method for y=1/f(x)
I need to know the Newton-Raphson equation for y=1/f(x)
I've tried to work it out, but I'm not sure if I'm right
I got this:
x = x + f'(x) / f(x)
EDIT> I've tried what I worked out and realised that it's horribly wrong.
I really need help :P
I don't understand why it's not working :'( I see what was wrong with what I originally got. I just made a simple mistake, but now I've got something which I'm sure is right, but won't work.
y = f(x) = 1 / g(x)
x = x - f(x) / f'(x)
= x - (1/g(x)) / (-g'(x)/g(x)^2)
= x - g(x)^2 / -g'(x) * g(x)
= x - g(x) / -g'(x)
= x + g(x) / g'(x)
I tried this too, and it didn't work.
I'm using this in a computer program, so I need to know if I'm using the wrong equation, or if a different part of the program is messing it up.
Yet another edit> I don't need this any more. I did something different instead. Sorry for the waste of time :P