function [fi, fj] = floor_force_i_j_param ( t, n, un, vn, i, j, h, hw, Epfloor, cpfloor )
    uiy = un(2*i); viy = vn(2*i);
    ujy = un(2*j); vjy = vn(2*n);
    pi = -Epfloor*uiy -cpfloor*viy;
    pj = -Epfloor*ujy -cpfloor*vjy;
    if (uiy <= 0)
        if (ujy <= 0)
            fi = (pi/3 + pj/6)*h*hw;
            fj = (pi/6 + pj/3)*h*hw;
        else
            fi = pi*h*hw/6 * uiy*(2*uiy-3*ujy)/((ujy-uiy)^2);
            fj = pi*h*hw/6 *           (uiy^2)/((ujy-uiy)^2);
        end
    else
        if (ujy <= 0)
            fi = pj*h*hw/6 *           (ujy^2)/((ujy-uiy)^2);
            fj = pj*h*hw/6 * ujy*(2*ujy-3*uiy)/((ujy-uiy)^2);
        else
            fi = 0;
            fj = 0;
        end
    end
end
