Changes the element's value in matrix

Hi!

I use this syntax to design the experiment:

dFF2=ff2n(3)

and the result is:

dFF2 =

     0 0 0
     0 0 1
     0 1 0
     0 1 1
     1 0 0
     1 0 1
     1 1 0
     1 1 1

I want the "0" value to be "-1" in the design of experiment matrix.
How to do it?