Hi! I want to solve a reaction-diffusion PDE non linear system to study Turing Patterns. I use PDETool from Command line and I notice a problem in setting periodic boundary conditions, because PDETool supports only Dirichlet or Neumann-Robin conditions: For example, if (x,y)->[0 a]X[0 b] is my analysis domain, I want: u(0,y,t)=u(a,y,t) u(x,0,t)=u(x,b,t) v(0,y,t)=v(a,y,t) v(x,0,t)=v(x