By: Tao Steven Zheng
1 import matplotlib.pyplot as plt
2 import numpy as np
3
4 '''Part 1: Calculating Derivatives on Python'''
5
6 h = 0.000000001 #step-size
7 return (f(x+h) - f(x))/h #definition of derivative
8
9 '''Part 2: Plot function with tangent'''
10
11 def tangent_line(f,x_0,a,b):
12 x = np.linspace(a,b,200)
13 y = f(x)
14 y_0 = f(x_0)
15 y_tan = deriv(f,x_0) * (x - x_0) + y_0
16
17 #plotting
18 plt.plot(x,y,'r-')
19 plt.plot(x,y_tan,'b-')
20 plt.axis([a,b,a,b])
21 plt.xlabel('x')
22 plt.ylabel('y')
23 plt.title('Plot of a function with tangent line')
24 plt.show()
25
26 '''Part 3: Tests and results'''
27 #Test number 1
28
29 def f1(x):
30 return x**2
31
32 tangent_line(f1,1,-2,2)
33
34 #Test number 2
35
36 def f2(x):
37 return np.exp(-x**2)
38
39 tangent_line(f2,1,-2,2)
Test 1
Test 2
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