13-gon at 5.37E-15(P27)

19-gon at 2.39E-15(P27)

11-gon at 8.02E-15(P29)

19-gon at 3E-14 (P37)

11-gon at 5.09E-14 (P37)

this method is complex but it is better than the way I found before. It is really difficult to reach E-15.

13-gon at 4.91E-14 (P32)

23-gon at 2.39E-15 (P32)

7-gon at 7.45E-15 (P22)

it took me a lot effort to reach this accuracy. I tried traditional way I used to be but failed. So I thought it might to have some new approch and this method is one . I just found that it is hard to use currecnt computer to find a good method at E-15 as the computer don't have enough lenth for the digits. I am happy to find this.