import numpy as np
import matplotlib.pyplot as plt

n = 100

x = np.linspace(0, 3*np.pi, n)
signal = np.cos(x)
plt.plot(signal, 'r')

mu_n = 0
sigma_n = 0.15

a = mu_n - np.sqrt(3)*sigma_n
b = mu_n + np.sqrt(3)*sigma_n

noise = np.random.uniform(a, b, n)
noisy_signal = signal + noise

plt.close('all')
plt.figure(1, figsize=(12, 9))
plt.plot(signal, 'r', label='signal')
plt.plot(noisy_signal, 'b-o', label='noisy_signal')
plt.legend()
plt.xlabel('x [rad]')
plt.grid()

# plt.savefig('plot_unif_noise.pdf')
plt.show()