*(r1::RemoteRef,r2::RemoteRef)=@spawnat r2.where fetch(r1)*fetch(r2)

function prefix8(y,*)
    if length(y)!=8; error("length 8 only"); end
    for i in [2,4,6,8]; y[i]=y[i-1]*y[i]; end
    for i in [  4,  8];   y[i]=y[i-2]*y[i]; end
    for i in [      8];    y[i]=y[i-4]*y[i]; end
    for i in [    6  ];   y[i]=y[i-2]*y[i]; end
    for i in [ 3,5,7 ]; y[i]=y[i-1]*y[i]; end
    y
end


function laplace_iter_vec(u, dx2, dy2, Niter, N)
   for i = 1:Niter
       u[2:N-1, 2:N-1] = ((u[1:N-2, 2:N-1] + u[3:N, 2:N-1])*dy2 + (u[2:N-1,1:N-2] + u[2:N-1, 3:N])*dx2) * (1./ (2*(dx2+dy2)))
   end
   return u
end

function laplace_iter_devec(u, dx2, dy2, Niter, N)
   uout = copy(u)
   for iter = 1:Niter
       for i = 2:N-1
           for j = 2:N-1 
               uout[i,j] = ((u[i-1,j]+u[i+1,j])*dy2 + (u[i,j-1]+u[i,j+1])*dx2 ) * (1./(2*(dx2+dy2)))
           end 
       end
       u, uout = uout, u
   end
   return u
end 

*(α::Number,  g::Function)= x->α*g(x)         # Scalar times function
*(f::Function,λ::Number)  = x->f(λ*x)         # Scale the argument
*(f::Function,g::Function)= x->f(g(x))        # Function Composition