Merge pull request sympy#26948 from oscarbenjamin/pr_zero_comparison_113

fix(core): make comparisons of Integer(0) and Float(0) consistent.

Author: oscarbenjamin

sympy/core/evalf.py

@@ -1494,15 +1494,15 @@ def evalf(x: 'Expr', prec: int, options: OPT_DICT) -> TMP_RES:
         re, im = as_real_imag()
         if re.has(re_) or im.has(im_):
             raise NotImplementedError
-        if re == 0.0:
+        if not re:
             re = None
             reprec = None
         elif re.is_number:
             re = re._to_mpmath(prec, allow_ints=False)._mpf_
             reprec = prec
         else:
             raise NotImplementedError
-        if im == 0.0:
+        if not im:
             im = None
             imprec = None
         elif im.is_number:

sympy/core/numbers.py

@@ -1597,8 +1597,6 @@ def __eq__(self, other):
             # S(0) == S.false is False
             # S(0) == False is True
             return False
-        if not self:
-            return not other
         if other.is_NumberSymbol:
             if other.is_irrational:
                 return False

sympy/core/tests/test_numbers.py

@@ -455,13 +455,27 @@ def eq(a, b):
         t = Float("1.0E-15")
         return (-t < a - b < t)
 
-    zeros = (0, S.Zero, 0., Float(0))
-    for i, j in permutations(zeros[:-1], 2):
-        assert i == j
-    for i, j in permutations(zeros[-2:], 2):
-        assert i == j
-    for z in zeros:
-        assert z in zeros
+    equal_pairs = [
+        (0, 0.0), # This is just how Python works...
+        (0, S.Zero),
+        (0.0, Float(0)),
+    ]
+    unequal_pairs = [
+        (0.0, S.Zero),
+        (0, Float(0)),
+        (S.Zero, Float(0)),
+    ]
+    for p1, p2 in equal_pairs:
+        assert (p1 == p2) is True
+        assert (p1 != p2) is False
+        assert (p2 == p1) is True
+        assert (p2 != p1) is False
+    for p1, p2 in unequal_pairs:
+        assert (p1 == p2) is False
+        assert (p1 != p2) is True
+        assert (p2 == p1) is False
+        assert (p2 != p1) is True
+
     assert S.Zero.is_zero
 
     a = Float(2) ** Float(3)

sympy/geometry/tests/test_point.py

@@ -418,7 +418,7 @@ def test_arguments():
     a = Point(0, 1)
     assert a/10.0 == Point(0, 0.1, evaluate=False)
     a = Point(0, 1)
-    assert a*10.0 == Point(0.0, 10.0, evaluate=False)
+    assert a*10.0 == Point(0, 10.0, evaluate=False)
 
     # test evaluate=False when changing dimensions
     u = Point(.1, .2, evaluate=False)

sympy/integrals/tests/test_integrals.py

@@ -2080,7 +2080,7 @@ def test_issue_20782():
     assert integrate(fun1, L) == 1
     assert integrate(fun2, L) == 0
     assert integrate(-fun1, L) == -1
-    assert integrate(-fun2, L) == 0.
+    assert integrate(-fun2, L) == 0
     assert integrate(fun_sum, L) == 1.
     assert integrate(-fun_sum, L) == -1.
 

sympy/physics/quantum/qubit.py

@@ -493,7 +493,7 @@ def matrix_to_qubit(matrix):
             element = matrix[0, i]
         if format in ('numpy', 'scipy.sparse'):
             element = complex(element)
-        if element != 0.0:
+        if element:
             # Form Qubit array; 0 in bit-locations where i is 0, 1 in
             # bit-locations where i is 1
             qubit_array = [int(i & (1 << x) != 0) for x in range(nqubits)]
@@ -582,7 +582,7 @@ def measure_all(qubit, format='sympy', normalize=True):
         size = max(m.shape)  # Max of shape to account for bra or ket
         nqubits = int(math.log(size)/math.log(2))
         for i in range(size):
-            if m[i] != 0.0:
+            if m[i]:
                 results.append(
                     (Qubit(IntQubit(i, nqubits=nqubits)), m[i]*conjugate(m[i]))
                 )

sympy/polys/matrices/tests/test_linsolve.py

@@ -32,7 +32,8 @@ def test__linsolve_float():
         y - x,
         y - 0.0216 * x
     ]
-    sol = {x:0.0, y:0.0}
+    # Should _linsolve return floats here?
+    sol = {x:0, y:0}
     assert _linsolve(eqs, (x, y)) == sol
 
     # Other cases should be close to eps

sympy/polys/tests/test_polytools.py

@@ -3033,7 +3033,7 @@ def test_nroots():
     eps = Float("1e-5")
 
     assert re(roots[0]).epsilon_eq(-0.75487, eps) is S.true
-    assert im(roots[0]) == 0.0
+    assert im(roots[0]) == 0
     assert re(roots[1]) == Float(-0.5, 5)
     assert im(roots[1]).epsilon_eq(-0.86602, eps) is S.true
     assert re(roots[2]) == Float(-0.5, 5)
@@ -3046,7 +3046,7 @@ def test_nroots():
     eps = Float("1e-6")
 
     assert re(roots[0]).epsilon_eq(-0.75487, eps) is S.false
-    assert im(roots[0]) == 0.0
+    assert im(roots[0]) == 0
     assert re(roots[1]) == Float(-0.5, 5)
     assert im(roots[1]).epsilon_eq(-0.86602, eps) is S.false
     assert re(roots[2]) == Float(-0.5, 5)

sympy/solvers/tests/test_numeric.py

@@ -73,12 +73,12 @@ def getroot(x0):
 
 def test_issue_6408():
     x = Symbol('x')
-    assert nsolve(Piecewise((x, x < 1), (x**2, True)), x, 2) == 0.0
+    assert nsolve(Piecewise((x, x < 1), (x**2, True)), x, 2) == 0
 
 
 def test_issue_6408_integral():
     x, y = symbols('x y')
-    assert nsolve(Integral(x*y, (x, 0, 5)), y, 2) == 0.0
+    assert nsolve(Integral(x*y, (x, 0, 5)), y, 2) == 0
 
 
 @conserve_mpmath_dps

sympy/utilities/tests/test_wester.py

@@ -269,7 +269,7 @@ def test_C24():
 
 
 def test_D1():
-    assert 0.0 / sqrt(2) == 0.0
+    assert 0.0 / sqrt(2) == 0
 
 
 def test_D2():