File:Speed of sound in water.png

"""
Plot of the speed of sound versus temperature in water

The data is obtained from "The Engineering Toolbox" [1]_


References
----------
.. [1] The Engineering Toolbox. Water - Speed of Sound.
    Accesed: April 27, 2015.
    http://www.engineeringtoolbox.com/sound-speed-water-d_598.html
"""
import numpy as np
import matplotlib.pyplot as plt
from matplotlib import rcParams
 
rcParams['font.family'] = 'serif'
rcParams['font.size'] = 16 

data = np.array([
       [    0.,  1403.],
       [    5.,  1427.],
       [   10.,  1447.],
       [   20.,  1481.],
       [   30.,  1507.],
       [   40.,  1526.],
       [   50.,  1541.],
       [   60.,  1552.],
       [   70.,  1555.],
       [   80.,  1555.],
       [   90.,  1550.],
       [  100.,  1543.]])
       
temp = data[:, 0]
vel = data[:, 1]

a3, a2, a1, a0 = np.polyfit(temp, vel, 3)
temp_fit = np.linspace(0,100)
vel_fit = a0 + a1*temp_fit + a2*temp_fit**2 + a3*temp_fit**3

plt.plot(temp, vel, 'o')
plt.plot(temp_fit, vel_fit, 'k')
plt.grid(True)
plt.xlabel(r"Temperature ($^\circ$C)")
plt.ylabel(r"Speed (m/s)")
plt.savefig("Speed_of_sound_in_water.svg")