Modular and Landen transformation between two kinds of separable   solutions of Sine Gordon equation in N=2
  In this article, we study on the separable N=2 solutions of Sine Gordon equation. From the original symmetry,we get two kinds of N=2 separable solutions. we find these two kinds are related to Landen transformation 
Nan-Hong Kuo, C.D. Hu
math-ph math.MP