import numpy as np
import matplotlib.pyplot as plt
import matplotlib.tri as mtri
from mpl_toolkits import mplot3d
from mpl_toolkits.mplot3d import Axes3D

coord = np.asarray([[0,0], 
                    [1,0],
                    [1,1],
                    [0,1],
                    [.5,.5]])
triangles = np.asarray([[0,1,4],
                        [1,2,4],
                        [2,3,4],
                        [3,0,4]])
dirichlet= np.array([[0,1],
                     [1,2],
                     [2,3],
                     [3,0]])
# show triangulation
plt.triplot(mtri.Triangulation(coord[:,0], coord[:, 1], triangles))
plt.show()
# plot the interpolation of the function x+y
func = lambda x, y:  x + y
func2=np.vectorize(func)
z=func2(coord[:,0],coord[:,1])
fig = plt.figure(figsize =(14, 9))
ax = plt.axes(projection ='3d')
trisurf = ax.plot_trisurf(coord[:,0],coord[:,1],z,
                          triangles = triangles, 
                          cmap =plt.get_cmap('summer'),
                          edgecolor='Gray');
plt.show()