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Book4_Ch02_Python_Codes/Bk4_Ch2_03.py

@@ -6,14 +6,31 @@
 # Beijing, China, 2022
 ###############
 
-# Bk4_Ch2_03.py
+# Bk4_Ch1_03.py
 
+import matplotlib.pyplot as plt
 import numpy as np
-a = np.array([[1,2],
-              [3,4]])
 
-b = np.array([[3,4],
-              [5,6]])
+x1 = np.linspace(-10, 10, num=201);
+x2 = x1;
 
-a_dot_b = np.vdot(a,b)
-# [1,2,3,4]*[3,4,5,6].T
+xx1, xx2 = np.meshgrid(x1,x2)
+p = 2
+zz = ((np.abs((xx1))**p) + (np.abs((xx2))**p))**(1./p)
+
+fig, ax = plt.subplots(figsize=(12, 12))
+
+ax.contour(xx1, xx2, zz, levels = np.arange(11), cmap='RdYlBu_r')
+
+ax.axhline(y=0, color='k', linewidth = 0.25)
+ax.axvline(x=0, color='k', linewidth = 0.25)
+ax.set_xlim(-12, 12)
+ax.set_ylim(-12, 12)
+ax.spines['top'].set_visible(False)
+ax.spines['right'].set_visible(False)
+ax.spines['bottom'].set_visible(False)
+ax.spines['left'].set_visible(False)
+ax.set_xlabel('$x_1$')
+ax.set_ylabel('$x_2$')
+ax.set_aspect('equal', adjustable='box')
+plt.show()