w 1 ( a , x ) = e − 1 4 i x 2 M ( tfrac 1 4 − tfrac 1 2 i a , tfrac 1 2 , tfrac 1 2 i x 2 ) = e 1 4 i x 2 M ( tfrac 1 4 + tfrac 1 2 i a , tfrac 1 2 , − tfrac 1 2 i x 2 )