feat(polys): Add DomainMatrix based on poly elements

Remove simplification in Wester test_Z3 as the results are determinstic
now.

sympy/utilities/tests/test_wester.py

@@ -20,7 +20,7 @@
     FiniteSet, elliptic_e, elliptic_f, powsimp, hessian, wronskian, fibonacci,
     sign, Lambda, Piecewise, Subs, residue, Derivative, logcombine, Symbol,
     Intersection, Union, EmptySet, Interval, idiff, ImageSet, acos, Max,
-    MatMul, conjugate, cancel)
+    MatMul, conjugate)
 
 import mpmath
 from sympy.functions.combinatorial.numbers import stirling
@@ -2996,15 +2996,10 @@ def test_Z3():
     r = Function('r')
     # recurrence solution is correct, Wester expects it to be simplified to
     # fibonacci(n+1), but that is quite hard
-    expected = 2**(-n)*(- sqrt(5)*(1 - sqrt(5))**n
-                        + 5*(1 - sqrt(5))**n
-                        + sqrt(5)*(1 + sqrt(5))**n
-                        + 5*(1 + sqrt(5))**n)/10
+    expected = ((S(1)/2 - sqrt(5)/2)**n*(S(1)/2 - sqrt(5)/10)
+              + (S(1)/2 + sqrt(5)/2)**n*(sqrt(5)/10 + S(1)/2))
     sol = rsolve(r(n) - (r(n - 1) + r(n - 2)), r(n), {r(1): 1, r(2): 2})
-    # XXX: We use cancel and radsimp because the output from rsolve is
-    # non-deterministic.
-    assert cancel(radsimp(sol)) == expected
-
+    assert sol == expected
 
 
 @XFAIL