helpin me with a fixed point method function

Hi, Im having difficulty coming up with a fixed point function; this is what i came up with: please tell me what modifications i shpuld make to this:

 function [root,y,ea,iter]=fixedpoint(func,x0,es,maxiter)
 iter=0;
 ea=100;
 g(x0)+x= func(x0);
 while (1)
 x0= root;
 root=g(root);
 iter = iter + 1;
 if xr ~= 0, ea = abs((root - x0)/root) * 100; 
 end
 if ea <= es | iter >= maxiter, break, end
 end
 y=func(root);
 end