new_contents: from pylab import *;
  import diffusion;
  import inversion; 
  import pSpectral;
  import inversion;
  
  ion();
  
  
  Nx = 128;
  Ny = 256;
  
  xx = linspace(0,2*pi-2*pi/Nx,Nx);
  yy = linspace(0,2*pi-2*pi/Ny,Ny);
  
  [x,y]=  meshgrid(xx,yy);
  a = sin(x)*sin(y)+cos(x)*sin(y);
  
  p = pSpectral.parSpectral(Nx,Ny);
  ip = inversion.specInv(Nx,Ny);
  
  c = p.laplacian(a);
  d = ip.invLaplacian(c);
  
subject: Test code for inversion.