JuMP v0.19: using JuMP, Clp m = Model(with_optimizer(Clp.Optimizer)) @variable(m, y>=0) @objective(m, Max, y) @constraint(m, con, y <= 3) JuMP.optimize!(m) pi_val = JuMP.result_dual(con) @show pi_val I obtained pi_val = -1.0 JuMP v0.18: using JuMP, Clp m = Model(solver=ClpSolver()) @variable(m, …

Result_dual vs getdual. signs are the opposite

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