1/16-m4=(1/4+m2)(1/4-m2)=(1/4+m2)(1/2+m)(1/2-m)
=(1/4+m2)(1/4-m2) =(1/4+m2)(1/2+m)(1/2-m)
=(¼+m2)(1/2+m)(1/2-m)
