.5ln|(s+2/(1+r+sqrt(3r^2-1))-1/(1+r))/(s-2/(1+r+sqrt(3r^2-1))+1/(1+r))|-0.3313329488624579555112,where r=(cbrt(108+12sqrt69)+cbrt(108-12sqrt69))/6,s=sqrt(1+sqrt2)(2/(sqrt2+r+sqrt(3r^2-1))-1/(sqrt2+r))