function [ X ] = mmq_montaX( FUNCAO, A )
%  [ X ] = mmq_montaX( FUNCAO, A );

Y0 = feval( FUNCAO, A );
X = zeros( length(Y0), length(A) );
for qA = length(A):-1:1
    Aplus = A;
    Aplus(qA) = A(qA) + 1e-3*abs(A(qA)) + 1e-10;
    Yplus = feval( FUNCAO, Aplus );
    X(:,qA) = (Yplus - Y0) / ( Aplus(qA) - A(qA) );
end
