improved some plots

RujalAcharya · Jan 17, 2024 · f31aa51 · f31aa51
1 parent 6accab6
commit f31aa51
Showing 1 changed file with 17 additions and 17 deletions.
diff --git a/lectures/03-Fourier-properties/plots-code/linearity.py b/lectures/03-Fourier-properties/plots-code/linearity.py
@@ -13,41 +13,41 @@
 
 plt.figure(1, figsize=(9.5, 7))
 plt.subplot(321)
-plt.title('real(x1) (amp=.5, freq=20)')
+plt.title('x1 (amp=.5, #periods=20)')
 plt.plot(np.arange(0, N, 1.0), np.real(x1), b, marker='x', ms=4, lw=1.5)
 plt.axis([0, N, -1, 1])
 
 plt.subplot(322)
-plt.title('real(x2) (amp=1, freq=25)')
+plt.title('x2 (amp=1, #periods=25)')
 plt.plot(np.arange(0, N, 1.0), np.real(x2), b, marker='x', ms=4, lw=1.5)
 plt.axis([0, N, -1, 1])
 X1 = fft(x1)
-mX1 = abs(X1)/N        
+mX1 = abs(X1[0:N//2-1])/N
 
 plt.subplot(323)
-plt.title('mX1 (amp=.5, freq=20)')
-plt.plot(np.arange(0, N, 1.0), mX1, 'r-x', ms=4, lw=1.5)
-plt.axis([0,N,0,1])
+plt.title('abs(X1)')
+plt.plot(np.arange(0, (N//2)-1, 1.0), mX1, 'r-x', ms=4, lw=1.5)
+plt.axis([0,(N//2)-1,0,1])
 X2 = fft(x2)
-mX2 = abs(X2)/N        
+mX2 = abs(X2[0:N//2-1])/N
 
 plt.subplot(324)
-plt.title('mX2 (amp=1, freq=25)')
-plt.plot(np.arange(0, N, 1.0), mX2, 'r-x', ms=4, lw=1.5)
-plt.axis([0,N,0,1])
+plt.title('abs(X2)')
+plt.plot(np.arange(0, N//2-1, 1.0), mX2, 'r-x', ms=4, lw=1.5)
+plt.axis([0,N//2-1,0,1])
 x = x1 + x2
 
 plt.subplot(325)
-plt.title('mX1+mX2')
-plt.plot(np.arange(0, N, 1.0), mX1+mX2, 'r-x', ms=4, lw=1.5)
-plt.axis([0, N, 0, 1])
+plt.title('abs(X1+X2)')
+plt.plot(np.arange(0, N//2-1, 1.0), mX1+mX2, 'r-x', ms=4, lw=1.5)
+plt.axis([0, N//2-1, 0, 1])
 X = fft(x)
-mX= abs(X)/N        
+mX= abs(X[0:N//2-1])/N
 
 plt.subplot(326)
-plt.title('DFT(x1+x2)')
-plt.plot(np.arange(0, N, 1.0), mX, 'r-x', ms=4, lw=1.5)
-plt.axis([0,N,0,1])
+plt.title('abs(DFT(x1+x2))')
+plt.plot(np.arange(0, N/2-1, 1.0), mX, 'r-x', ms=4, lw=1.5)
+plt.axis([0,N/2-1,0,1])
 
 plt.tight_layout()
 plt.savefig('linearity.png')