function[gamma,xy0,xyc,c] = LumpedVortex(xy1,xy2,alpha,U0)
% Vortices Concentrados
%
% [gamma] = LumpedVortex(c,xy1,xy2,alpha,U0)


% Calcula x0 e y0
xy0   = xy1*3/4 + xy2/4;
xyc   = xy1/4 + xy2*3/4;

% Calcula a corda do elemento
c = sqrt(sum((xy2-xy1).^2,2));

% calcula n, vetor normal no ponto de colocação
nhat = (xy2-xy1)./(c*[1 -1]);
nhat = nhat(:,[2 1]);

% Calcula o vetor b do sistema linear
Vuf = U0*[cos(alpha) sin(alpha)];
rhs = -nhat*Vuf';

% Calcula a matriz de influência aerodinâmica
a = zeros(length(xy1(:,1)));
for i=1:length(xy1(:,1))
    for j=1:length(xy1(:,1))
        V=vort2D(xy0(j,:),xyc(i,:),1);
        a(i,j) = nhat(i,:)*V;
    end
end

gamma = inv(a)*rhs;

end