# coding: utf-8

# # Three little quadratic functions

# In[2]:

get_ipython().magic(u'matplotlib qt')


# In[1]:

import numpy as np
import matplotlib.pyplot as pt


# Consider the three equations:
# 
# $$y=x^2+\delta$$
# $$z=x^2-\delta$$
# $$y=z^2+\delta$$

# In[2]:

delta = 0.5


# In[5]:


from mpl_toolkits.mplot3d import Axes3D
fig = pt.figure()
ax = fig.add_subplot(111, projection='3d')

res = 10j

x, z = np.mgrid[-3:3:res,-3:3:res]
y = x**2 + delta

ax.plot_surface(x, y, z, color="red", cstride=1, rstride=1)

if 1:
    y, x = np.mgrid[-3:3:res,-3:3:res]
    z = x**2 - delta
    
    ax.plot_surface(x, y, z, color="green", cstride=1, rstride=1)

if 0:
    x, z = np.mgrid[-3:3:res,-3:3:res]
    y = z**2 + delta
    
    ax.plot_surface(x, y, z, color="blue", cstride=1, rstride=1)


# Need better plotting tool. See corresponding `three-quadratics.py`.