2⁢ⅈ⁢K⁢k′⁢nd⁡(2⁢K⁢t,k)=limN→∞⁡∑n=-NN(-1)n⁢πtan⁡(π⁢(t+12-(n+12)⁢τ))=limN→∞⁡∑n=-NN(-1)n⁢limM→∞⁡(∑m=-MM1t+12-m-(n+12)⁢τ),