let me write the standard qpex1 example in docplex:
from docplex.mp.model import Model
mdl = Model(name='qpex1')
#decision variables
x = {b: mdl.continuous_var(0,40,name="x"+str(b)) for b in range(0,3)}
# Constraint
mdl.add_constraint( - x[0] + x[1] + x[2] <= 20, 'ct1')
mdl.add_constraint(x[0] - 3 * x[1] + x[2] <= 30,'ct2');
# Objective
mdl.maximize(x[0] + 2 * x[1] + 3 * x[2]-
0.5 * ( 33*x[0]*x[0] + 22*x[1]*x[1] + 11*x[2]*x[2] -
12*x[0]*x[1] - 23*x[1]*x[2] ))
msol=mdl.solve()
# Dislay solution
for v in mdl.iter_continuous_vars():
print(v," = ",v.solution_value)
print("objective : ",msol.get_objective_value() )
which gives
x0 = 0.13911493492690713
x1 = 0.5984654737750436
x2 = 0.8983957227089207
objective : 2.0156165232891574
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