1. zeta function regularization:
1+1+1+1+....... = -1/2
1+2+3+4+........= -1/12 ( not Abel summable)
1-2+3-4+........= 1/4 ( Abel summable )
2. geometric series:
1+2+4+8+...... = -1 ( Abel summable; not Borel summable )
1-2+4-8+.......= 1/3 ( Borel summable )
1-1+1-1+.......= 1/2 ( Grandi's series; Borel summable )
你以為我在胡搞?
