x = 0:0.5:12;
y = x;
[xx, yy] = meshgrid(x,y);

u = zeros(size(xx));

for k=0:50
  n = 2*k + 1;
  u = u + sinh(n*pi*xx/12) .* sin(n*pi*yy/12) ./ (n * sinh(n*pi));
end

u = u * 400 / pi;

surf(x,y,u)
