function [xn,a,b,c]=mull1(f,x0,x1,x2)
% function xn=mull1(f,x1,x2,x3)
% Mullerova metoda  pro reseni rovnice f(x)=0 - 1 iterace

x=x0;
f0=eval(f);
x=x1;
f1=eval(f);
x=x2;
f2=eval(f);
c=f2;
b=((x0-x2)^2*(f1-f2)-(x1-x2)^2*(f0-f2))/((x0-x2)*(x1-x2)*(x0-x1));
a=((x1-x2)*(f0-f2)-(x0-x2)*(f1-f2))/((x0-x2)*(x1-x2)*(x0-x1));
sig=(b>0)*2-1;
xn=x2-2*c/(b+sig*sqrt(b^2-4*a*c));
