import numpy as np
import matplotlib.pyplot as plt

x = np.array([0, 1, 2, 3, 4, 5])
y = x
z = np.sqrt(x)

plt.close('all')
plt.figure(1, figsize=(12, 9))
plt.plot(x, y, 'r*-')
plt.plot(x, z, 'bo-')
plt.xlabel('x [s]')
plt.ylabel('[m]')
plt.grid()
plt.legend(('y', 'z'))

plt.savefig('plott1.pdf')
plt.show()