add wave genration functions

src/generate_sine.m

@@ -0,0 +1,15 @@
+function x = generate_sine(amplitude, frequency, phase, fs, duration)
+%GENERATE_SINE:Arthur Lu returns a matrix of sampled sine wave, where the
+%phase shift is in number of periods
+    x = zeros(1, fs * duration);
+    A = amplitude;
+    f = frequency;
+    p = phase;
+    n = fs * duration;
+    dt = 1 / fs;
+    for i = 1:n
+        t = i * dt;
+        x(i) = A * sin(2 * pi * f * t - p);
+    end
+end
+

src/generate_square.m

@@ -0,0 +1,20 @@
+function x = generate_square(amplitude, frequency, phase, fs, duration, duty)
+%GENERATE_SINE:Arthur Lu returns a matrix of sampled sine wave, where the
+%phase shift is in number of periods
+    x = zeros(1, fs * duration);
+    A = amplitude;
+    f = frequency;
+    p = phase;
+    n = fs * duration;
+    dt = 1 / fs;
+    for i = 1:n
+        t = i * dt;
+        st = mod(f * t - p, 1);
+        if(st < duty)
+            x(i) = A;
+        else
+            x(i) = -A;
+        end
+    end
+end
+

src/generate_triangle.m

@@ -0,0 +1,19 @@
+function x = generate_triangle(amplitude, frequency, phase, fs, duration, duty)
+%GENERATE_SINE:Arthur Lu returns a matrix of sampled sine wave, where the
+%phase shift is in number of periods
+    x = zeros(1, fs * duration);
+    A = amplitude;
+    f = frequency;
+    p = phase;
+    n = fs * duration;
+    dt = 1 / fs;
+    for i = 1:n
+        t = i * dt;
+        st = mod(f * t - p, 1);
+        if(st < duty)
+            x(i) = A*(1/duty * st - 0.5);
+        else
+            x(i) = A*(-(1/(1-duty))*st + (duty/(1-duty)) + 1 - 0.5);
+        end
+    end
+end

src/play_wave.m

@@ -0,0 +1,5 @@
+function play_wave(wave, fs)
+%PLAY_WAVE:Arthur Lu plays a wave as sound
+    sound(wave, fs)
+end
+

src/plot_wave.m

@@ -0,0 +1,8 @@
+function plot_wave(waveform, fs, duration)
+%PLOT_WAVE:Arthur Lu plots a waveform
+    x = linspace(0, duration, fs * duration);
+    plot(x, waveform);
+    xlabel("time");
+    ylabel("amplitude");
+end
+