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%% GRAVITATIONAL TERM

%gravitational term
g0 = [0 -g 0]'
g1 = simplify(-m1*g0'*JP_l1(:,1) - m2*g0'*JP_l2(:,1))
g2 = simplify(-m1*g0'*JP_l1(:,2) - m2*g0'*JP_l2(:,2))

G = [g1 g2]'