[Matlab] MetodaPolowieniaIEkstremum

function [ x ] = dzielenieNaPolowe( f, a,b, E )
    syms x
    f = eval(f);

    while abs(b-a) > 2*E
        xm = (a+b)/2;
        l = b-a;
        x1 = a+l/4;
        x2 = b-l/4;
        if subs(f,x1) < subs(f,xm)
            b = xm;
            l = b - a;
            xm = x1;
        elseif subs(f,x2) < subs(f,xm)
            a = xm;
            l = b - a;
            xm = x2;
        else
            a = x1;
            b = x2;
            l = b-a;
        end
    end
    x = (a+b)/2;
end