function main
clc
format long

    step = 0.01;
    cur_x = 0.0;
    derivs_my_1 = [];
    derivs_my_2 = [];
    derivs_1 = [];
    derivs_2 = [];
    syms xx;
    derivative1 = diff(tan(2 * xx))
    derivative2 = diff(derivative1)
    my_func = @func
    while (cur_x <= 1.0)
        derivs_1 = [derivs_1, vpa(subs(derivative1, xx, cur_x))];
        derivs_2 = [derivs_2, vpa(subs(derivative2, xx, cur_x))];
        derivs_my_1 = [derivs_my_1, calc_deriv(cur_x, my_func, 1)];
        derivs_my_2 = [derivs_my_2, calc_deriv(cur_x, my_func, 2)];
        cur_x = cur_x + step;
    end
    derivs_2
    derivs_my_2
end

function F = func(x)
%     write your stupid function here
    F = tan(2 * x);
end

function F = calc_deriv(x, func, power)
    increment = 1e-5;
    if power == 1
        F = (func(x + increment) - func(x)) / increment;
    else
        f1 = (func(x + increment) - func(x)) / increment;
        f2 = (func(x + 2 * increment) - func(x + increment)) / increment;
        F = (f1 - f2) / increment;
    end
end