2⁢a⁢b⁢I⁡(e5)=a3⁢I⁡(0)-I⁡(e3)=a3⁢I⁡(0)-r+2⁢r-2⁢I⁡(-e3)=2⁢a⁢b⁢(I⁡(0)-r-2⁢I⁡(e1-e3)),