pkg load msh
pkg load fem-fenics

fem_init_env ();
problem = 'Biharmonic';
fem_create_all (problem);

x = y = linspace (0, 1, 32);
msho = msh2m_structured_mesh (x, y, 1, 1:4);
mshd = fem_init_mesh (msho);

V  = fem_fs_Biharmonic (mshd);

bc = fem_bc (V, @(x,y) 0, 1:4);
 

f = fem_coeff ('f', @(x,y) 4.0*pi^4.*sin(pi.*x).*sin(pi.*y));

g = fem_coeff ('alpha', @(x,y) 8);

A = fem_rhs_Biharmonic (V, bc, g);
b = fem_lhs_Biharmonic (V, bc, f );

u = A \ b;


func = fem_func ('u', V, u);
fem_plot (func);