def test_surplus_tax(self):
"""Practice problem 2.3
"""
sp.var('x p W')
benefit = et.benefit_from_demand(x, p, 100 - p)
sp.plot(benefit, (x, 0, 100))
cons = Consumer(x, p, benefit)
cons_sub = Consumer(x, p, benefit, other=W - x*p/2)
self.assertEqual(cons_sub.surplus().subs(p, 50) - cons.surplus().subs(p, 50),
1562.5)
def test_surplus(self):
"""Practice problem 2.2
"""
sp.var('A x p')
cons = Consumer(x, p, 2*A * sp.sqrt(x))
self.assertEqual(sp.piecewise_fold(cons.surplus()),
sp.Piecewise((0, p < 0),
(-A**2/p + 2*A*sp.sqrt(A**2/p**2), True)))
self.assertEqual(sp.piecewise_fold(cons.surplus_at(p*2)),
sp.Piecewise((0, 2*p < 0),
(-A**2/(2*p) + A*sp.sqrt(A**2/p**2), True)))
def test_surplus(self):
"""Practice problem 2.2
"""
sp.var('A x p')
cons = Consumer(x, p, 2 * A * sp.sqrt(x))
self.assertEqual(
sp.piecewise_fold(cons.surplus()),
sp.Piecewise((0, p < 0),
(-A**2 / p + 2 * A * sp.sqrt(A**2 / p**2), True)))
self.assertEqual(
sp.piecewise_fold(cons.surplus_at(p * 2)),
sp.Piecewise((0, 2 * p < 0),
(-A**2 / (2 * p) + A * sp.sqrt(A**2 / p**2), True)))
def test_surplus_tax(self):
"""Practice problem 2.3
"""
sp.var('x p W')
benefit = et.benefit_from_demand(x, p, 100 - p)
sp.plot(benefit, (x, 0, 100))
cons = Consumer(x, p, benefit)
cons_sub = Consumer(x, p, benefit, other=W - x * p / 2)
self.assertEqual(
cons_sub.surplus().subs(p, 50) - cons.surplus().subs(p, 50),
1562.5)
