Hi, I am new to FreeFem++, and I am trying to solve a BVP to obtain the micropolar strain localization tensor in a 2D square with some periodic boundary conditions that its dimensions are as follows: [-0.5,0.5]×[-0.5,0.5]. I have four unknowns, h1,h2,h3, and h4.

The boundary conditions are

h1(-0.5,y)+ h3(-0.5,y)= h1(0.5,y)+ h3(0.5,y)

h2(-0.5,y)+ h4(-0.5,y)= h2(0.5,y)+ h4(0.5,y)

h1(x,-0.5)+ h3(x,-0.5)= h1(x,0.5)+ h3(x,0.5)

h2(x,-0.5)+ h4(x,-0.5)= h2(x,0.5)+ h4(x,0.5)

I have a problem with defining these boundary conditions in FreeFem++.

I would appreciate it if you could help me with this.