function rhs = SwiftH_rhs(uF,time)
%
%  2D swift-hoh with ETD -- set-up -- djm, 26 jan 2007
%  - cubic nonlinearity w/ de-aliasing
%

global Nx Ny Ny32 Nx32 ixpad iypad kg lg

%  cubic SH with de-aliasing
if(1==1)
    uDF   = zeros(Ny32,Nx32); uDF(iypad,ixpad)  = uF;
    uD    = real(ifft2(uDF));
    rhsF  = fft2(-uD.^3)*(9/4)*(9/4);
end

%  quad SH with de-aliasing
if(0==1)
    uDxF  = zeros(Ny32,Nx32); uDxF(iypad,ixpad) = i*kg.*uF;
    uDx   = real(ifft2(uDxF));

    uDyF  = zeros(Ny32,Nx32); uDyF(iypad,ixpad) = i*lg.*uF;
    uDy   = real(ifft2(uDyF));

    rhsF  = fft2(-uDx.*uDy)*(9/4);
end

rhs   = rhsF(iypad,ixpad);
rhs(Ny/2+1,:) = 0;  rhs(:,Nx/2+1) = 0;

return