> >          # Set up the scalar |k| grid. Generally, for a box size of L (in one dimension), the grid
> > -        # spacing in k_x or k_y is Delta k=2pi/L.
> > -        self.k=2.*np.pi*((kx/(pixel_size*nx))**2+(ky/(pixel_size*ny))**2)**0.5
> > +        # spacing in k_x or k_y is Delta k=2pi/L (Barney edit: sqrt faster than **.5 I think...)
> > +        self.k = 2. * np.pi * np.sqrt((i_kx / (pixel_size * nx))**2 + (i_ky / (pixel_size * ny))**2)
> Either this or the calculation of _cos, _sin is wrong when nx != ny. It might be easier if you just don't let them be different, so L = nx*pixel_size is the same for both kx and ky.
> 
Yes, I know that. My thinking was that since PowerSpectrum doesn't ever call PowerSpectrumRealizer with ```nx!=ny```, it was okay as long as there's a comment about it.  But if you think that users are likely to use PowerSpectrumRealizer directly, then yes, I guess this should be changed.  I just didn't think that was likely at all.