Thursday, Feb 23, 2017
Let's look at some these product solutions:
Another way of visualizing them:
from numpy import * %matplotlib inline import matplotlib.pyplot as pl M = 7 x = linspace(-1,1,500) y = linspace(-1,1,500) X,Y = meshgrid(x,y) R = sqrt(X*X+Y*Y) Theta = arctan2(Y,X) pl.figure(figsize=(4,2*M)) for nm1 in range(M): n = nm1+1 pl.subplot(M,2,2*n-1) Z = R**n*cos(n*Theta) # evaluation of the function on the grid Z[R>1]=0 im = pl.imshow(Z,cmap=pl.cm.bwr) # drawing the function pl.xticks([]); pl.yticks([]) pl.subplot(M,2,2*n-1+1) Z = R**n*sin(n*Theta) # evaluation of the function on the grid Z[R>1]=0 im = pl.imshow(Z,cmap=pl.cm.bwr) # drawing the function pl.xticks([]); pl.yticks([]) pl.savefig('disk_eigenfunctions.png')
from mpl_toolkits.mplot3d import Axes3D M = 7 r = linspace(0,1,30) theta = linspace(0,2*pi,250) R,Theta = meshgrid(r,theta) X = R*cos(Theta) Y = R*sin(Theta) fig = pl.figure(figsize=(8,4*M)) for nm1 in range(M): n = nm1+1 Z = R**n*cos(n*Theta) # evaluation of the function on the grid #Z[R>1]=0 ax = fig.add_subplot(M,2,2*n-1, projection='3d') ax.plot_surface(X, Y, Z, cmap=pl.cm.cool,linewidth=0, antialiased=True) pl.xticks([]); pl.yticks([]) pl.subplot(M,2,2*n-1+1) Z = R**n*sin(n*Theta) # evaluation of the function on the grid #Z[R>1]=0 ax = fig.add_subplot(M,2,2*n-1+1, projection='3d') ax.plot_surface(X, Y, Z, cmap=pl.cm.cool,linewidth=0, antialiased=True) pl.xticks([]); pl.yticks([]) pl.savefig('disk_eigenfunctions_3d.png') # Why so few facets??
Definition
Periodic extension of f on [-L,L).
Convergence? Let's explore a little ...