-

고려대학교특강/fourier_sound_examples.m

@@ -0,0 +1,46 @@
+clear; close all; clc;
+
+fs = 50e3;
+
+t = 0:1/fs:1-1/fs;
+yy1 = 0.7*sin(2*pi*200*t);
+yy2 = sin(2*pi*350*t);
+
+sound(yy1, fs)
+sound(yy2, fs)
+sound(yy1+yy2, fs)
+
+%%
+figure('position',[68.2, 441, 984, 206]);
+plot(t, yy1);
+xlim([0, 0.05])
+hold on;
+xlabel('time(s)');
+set(gca,'fontsize',12);
+grid on;
+
+figure('position',[68.2, 441, 984, 206]);
+plot(t,yy2);
+xlim([0, 0.05])
+xlabel('time(s)');
+set(gca,'fontsize',12);
+grid on;
+
+
+figure('position',[68.2, 441, 984, 206]);
+plot(t, yy1+yy2);
+xlim([0, 0.05])
+xlabel('time(s)');
+set(gca,'fontsize',12);
+grid on;
+
+%%
+Y = zeros(1,500);
+Y(200) = 0.7;
+Y(350) = 1;
+figure;
+stem(Y,'linewidth',2)
+grid on;
+xlabel('frequency (Hz)');
+ylabel('Amplitude');
+set(gca,'fontsize',12)

기초수학/허근의위치/z_squared_plus_1.m

@@ -53,8 +53,8 @@
 
 %% complex space
 
-real_axis=linspace(-2,2,30);
-imag_axis=linspace(-2,2,30);
+real_axis=-2:0.1:2;
+imag_axis=-2:0.1:2;
 
 fz= zeros(length(real_axis),length(imag_axis));
 for iter_r=1:length(real_axis)
@@ -64,7 +64,8 @@
     end
 end
 figure;
-surf(real_axis,imag_axis,abs(fz'),angle(fz'));
+% surf(real_axis,imag_axis,abs(fz'),angle(fz'));
+surf(real_axis,imag_axis,abs(fz'),abs(fz'));
 xlabel('Real(f(z))');
 ylabel('Imag(f(z))');
 zlabel('Mag(f(z))');