http://benji3up2kxewkqfcq7buxk2xd6zwy3zggnurkrm3l4cvwy2iipvyyad.onion/mirrors/gmpdoc/Higher-degree-Toom_0027n_0027half.html
Toom’n’half means that the existence of one more piece is considered for a
single operand. It can be virtual, i.e. zero, or real, when the two operands
are not exactly balanced. By choosing an even r ,
Toom- r+1/2 requires 2r points, a multiple of four. The quadruplets of points include 0, inf , +1, and +-2^i , +-2^-i .