User Defined Function: multiply array by a constant

I am obvioulsy a beginner, but using excel VBA, how do i multiply an array by a constant?

I have tried many ways... why doesnt this work? I am getting it to return the third element in the array multiplied by 2 just to see if it works...user just selects an array


Function multiply(a)
For i = 1 To 4
a(i) = 2 * a(i)
Next i
multiply = a(3)
End Function

I would prefer not to do it element by element... any advice?

Thanks