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