newtzero

Finds the root(s) of a function of one variable, including complex roots, using Newton's method.

Description

NEWTZERO(f,xr,n,tol) finds roots of function f near guess xr with n iterations to tolerance tol. May find more than one root, even if guess is way off. NEWTZERO often works to find complex roots where FZERO fails. See examples in help.
The initial guess, number of iterations, and tolerance are optional arguments.

NEWTZERO finds the roots of functions of only one variable!

Please email me about bugs or other concerns. Thanks.

• MATLAB release: MATLAB 7.4 (R2007a)

[clement marchand]

Nice work

[mike owens]

Novel approach works well. Good job!

[Mike Zand]

Me likey. Well done.

[Yang Xiao]

The program can't work for the fuction:
     f(x) = det(eye(2)*x-[-0.8333 -0.0278;500.0000 -10.0000]-[-0.8333 -0.0167;0 0]*exp(-0.01*x))
  However, fzero.m of Matlab can find the root of the function. Please check your program, and relpy me.

[Jimmy Banker]

when i run it, it throw up an error

Error in ==> newt2 at 20
if f(xr) == 0, root = xr; return, end

whats wrong with it?

[taoufik brahim]

i think it's good mathematical idea but it not work execellent with complex nonliear algébric equation

thanks

[matt fig (author)]

Taoufik tried to apply this root finder to an implicitly defined function of the form:

T(m) = ((T^4-const)/const + f(m))

This file only works on explicitly defined functions of one variable.

[Kalid M]

Great work

[Andrew O'Connor]

Absolutely awsome. fzero was very unstable and gave single answers which were often incorrect when near the boundies. This program gave ALL solutions to the equation with almost no dependance on the guess. Thanks Matt

[Fabro]

Very helpfull, u deserve 10 stars... at list, I give u 5

[Nate]

Great Work. Solves equations far from initial guess where fzero fails