fixedpoint.m:

function [ x, k ] = fixed_point( gfunc, x0, atol, nmax )

xk = rand; % Just to start the while loop.

res = xk - x0;

k = 0; % Iteration index.

iflag = 0;

while abs(res)>atol

xk = feval(gfunc,x0); % x_{k+1} = g(x_{k})

res = xk - x0;

x0 = xk;

k = k + 1;

if(k == nmax)

iflag = -1;

break;

end

end

if(iflag==0)

k = k + 1;

x = xk;

else

disp(' maximum number of iterations reached!');

x = [];

k = [];

end

end

Using the m-file "fixed point.m", find the three roots of with lzk+1