function rhs=rhs(t,uv,dummy,D1,B,dx,n)

u2=uv(1:n^2); v2=uv(n^2+1:2*n^2);
urhs=(D1/dx^2)*B*u2+u2.*v2;
vrhs=(D1/dx^2)*B*v2+u2.*v2;
rhs=[urhs; vrhs];