from __future__ import division
import numpy as np
import matplotlib.pyplot as plt
from scipy.interpolate import interp1d


# Interpolation data
x = np.linspace(-2, 2, 15)
y = x**2 + np.sin(2*np.pi*x)
f = interp1d(x, y, kind='quadratic')

# Fine data
x = np.linspace(-2, 2, 200)
y = x**2 + np.sin(2*np.pi*x)

# Plots
fig = plt.figure(figsize=(4.5, 1))
ax = plt.subplot(1, 1, 1)
plt.plot(x, y, lw=2, zorder=6)
plt.plot(x, f(x), '--r', lw=2, zorder=7)
plt.ylim(-1.5, 4.75)
plt.xticks([-2, -1, 0, 1, 2])
plt.yticks([0, 2, 4])
plt.grid(b=True, lw=2, color='gray', linestyle='solid', alpha=0.5,
         zorder=3)
ax.spines['right'].set_color('none')
ax.spines['top'].set_color('none')
plt.savefig('Integration_simpson.svg', bbox_inches='tight')
plt.show()