Question

1. (10 pts) Write a single .py file program to plot the following functions on the same graph for x values from –π to π :

y1 = cos(x)

y2 = cos(2x)

y3 = cos(3x)

Plot specifications:

1. Choose an appropriate increment to generate smooth curves and add a comment in the code as to the rationale for that increment to receive full credit
2. y1 is red and dashed
3. y2 is blue and solid
4. y3 is black and dotted
5. Add a legend encompassing all three plots
6. Add an appropriate X-axis label
7. Add an appropriate Y-axis label
8. Add an appropriate Title
9. To receive full credit, header and code comments are required
10. (10 pts) Write a single .py file program to plot the following functions on the same graph for x values from –π to π :

11. y1 = cos(x)

    y2 = cos(2x)

    y3 = cos(3x)

    Plot specifications:

12. Choose an appropriate increment to generate smooth curves and add a comment in the code as to the rationale for that increment to receive full credit
13. y1 is red and dashed
14. y2 is blue and solid
15. y3 is black and dotted
16. Add a legend encompassing all three plots
17. Add an appropriate X-axis label
18. Add an appropriate Y-axis label
19. Add an appropriate Title
20. To receive full credit, header and code comments are required

Answer 1

Code:

import numpy as np
import matplotlib.pyplot as plt
%matplotlib inline

x = np.arange(-np.pi, np.pi+0.1,0.1) #0.1 will make enough points
# so that curve looks smooth
y1 = np.cos(x)
y2 = np.cos(2*x)
y3 = np.cos(3*x)

fig=plt.figure(figsize=(16, 6 ))
fig.suptitle('3 cosine variations', fontsize=16)

fig.add_subplot(1,3 , 1)
plt.plot(x ,y1, 'r--', linewidth= 2, label = "cos(x)")
plt.xlabel('x')
plt.ylabel('cos(x)')
plt.legend()

fig.add_subplot(1,3 , 2)
plt.plot(x ,y2, 'b-', linewidth= 2, label = "cos(2x)")
plt.xlabel('x')
plt.ylabel('cos(2x)')
plt.legend()

fig.add_subplot(1,3 , 3)
plt.plot(x ,y2, 'k-.', linewidth= 2, label = "cos(3x)")
plt.xlabel('x')
plt.ylabel('cos(3x)')
plt.legend()

Output:

cos(x) cos(2x) - cos(3x)