diff --git a/semestralka/1.m b/semestralka/1.m
index 1a3ca05..8f54119 100644
--- a/semestralka/1.m
+++ b/semestralka/1.m
@@ -7,26 +7,37 @@ rawText = fileread('data6.dat');
 nums = regexp(rawText, '[-+]?\d+', 'match');
 data = int16(str2double(nums));
 
-X = DFT_priama(double(data))
-n = length(X)
+X = DFT_priama(double(data));
+n = length(X);
 Fs = 200;
-freq = (0:n-1)*Fs/n
+freq = (0:n-1)*Fs/n;
 
 figure;
 plot(double(data));
 figure;
 plot(freq, X)
+%3
 figure;
-x = double(data);
-x = x - mean(x);
-plot(x); % centrovane data
+magX = abs(X);
+plot(freq, magX)
+% freq shift pre -Fs/2 po Fs/2
+freq_shift = (-n/2:n/2-1)*(Fs/n);
+%4
 figure;
-plot(freq, abs(X))
+subplot(2,1,1);
+plot(freq_shift, real(fftshift(X)), 'b');
+subplot(2,1,2);
+plot(freq_shift, imag(fftshift(X)), 'r');
+%5
+figure;
+plot(freq, imag(X), 'r');
+%6
+figure;
+plot(freq, real(X), 'r');
 figure;
 plot(freq, angle(X))
 
-magX = abs(X);
-[pks, locs] = findpeaks(magX, 'NPeaks', 6, 'SortStr', 'descend');
-
-f0 = freq(locs);
-disp(f0);
+[pks, locs] = findpeaks(magX, 'NPeaks', 10, 'SortStr', 'descend');
+f0 = freq(locs)
+f0b = f0(f0 < 100);
+f0_ohranicene = f0b
diff --git a/semestralka/2.m b/semestralka/2.m
new file mode 100644
index 0000000..75c6056
--- /dev/null
+++ b/semestralka/2.m
@@ -0,0 +1,29 @@
+clc;
+close all;
+clear all;
+
+f0_ohranicene = [25, 20, 10, 12.5];
+% semestralka
+rawText = fileread('data6.dat');
+nums = regexp(rawText, '[-+]?\d+', 'match');
+data = int16(str2double(nums));
+
+Fs = 200;
+r = 0.95;
+b = 1;
+a = 1;
+
+for k = 1:length(f0_ohranicene)
+    theta = 2*pi*(f0_ohranicene(k)/Fs);
+    b = conv(b, [1, -2*cos(theta), 1]);
+    a = conv(a, [1, -2*r*cos(theta), r^2]);
+end
+
+figure;
+zplane(b, a);
+figure;
+freqz(b, a);
+figure;
+freqz(b, a);
+filtered_data = filter(b, a, double(data));
+plot(filtered_data);
diff --git a/semestralka/docs.txt b/semestralka/docs.txt
new file mode 100644
index 0000000..5e9d02d
--- /dev/null
+++ b/semestralka/docs.txt
@@ -0,0 +1,2 @@
+https://en.wikipedia.org/wiki/Infinite_impulse_response
+https://courses.physics.illinois.edu/ece401/fa2020/slides/lec15.pdf