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- from sympy.holonomic.recurrence import RecurrenceOperators, RecurrenceOperator
- from sympy.core.symbol import symbols
- from sympy.polys.domains.rationalfield import QQ
- def test_RecurrenceOperator():
- n = symbols('n', integer=True)
- R, Sn = RecurrenceOperators(QQ.old_poly_ring(n), 'Sn')
- assert Sn*n == (n + 1)*Sn
- assert Sn*n**2 == (n**2+1+2*n)*Sn
- assert Sn**2*n**2 == (n**2 + 4*n + 4)*Sn**2
- p = (Sn**3*n**2 + Sn*n)**2
- q = (n**2 + 3*n + 2)*Sn**2 + (2*n**3 + 19*n**2 + 57*n + 52)*Sn**4 + (n**4 + 18*n**3 + \
- 117*n**2 + 324*n + 324)*Sn**6
- assert p == q
- def test_RecurrenceOperatorEqPoly():
- n = symbols('n', integer=True)
- R, Sn = RecurrenceOperators(QQ.old_poly_ring(n), 'Sn')
- rr = RecurrenceOperator([n**2, 0, 0], R)
- rr2 = RecurrenceOperator([n**2, 1, n], R)
- assert not rr == rr2
- # polynomial comparison issue, see https://github.com/sympy/sympy/pull/15799
- # should work once that is solved
- # d = rr.listofpoly[0]
- # assert rr == d
- d2 = rr2.listofpoly[0]
- assert not rr2 == d2
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