Add regression test

Closes sympy/sympy#21651
skirpichev · Jun 23, 2021 · cb13231 · cb13231
1 parent 658d59b
commit cb13231
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Showing 2 changed files with 11 additions and 3 deletions.
diff --git a/diofant/tests/concrete/test_sums_products.py b/diofant/tests/concrete/test_sums_products.py
@@ -3,9 +3,9 @@
 from diofant import (And, Catalan, Derivative, E, Eq, EulerGamma, Float,
                      Function, I, Integer, Integral, KroneckerDelta, Le, Mod,
                      Ne, Or, Piecewise, Product, Rational, Sum, Symbol,
-                     binomial, cos, exp, factorial, gamma, harmonic, log,
-                     lowergamma, nan, oo, pi, product, simplify, sin, sqrt,
-                     summation, symbols, sympify, zeta)
+                     binomial, cos, exp, factorial, floor, gamma, harmonic,
+                     log, lowergamma, nan, oo, pi, product, simplify, sin,
+                     sqrt, summation, symbols, sympify, zeta)
 from diofant.abc import a, b, c, d, k, m, x, y, z
 from diofant.concrete.summations import telescopic
 
@@ -920,3 +920,10 @@ def test_sympyissue_21557():
     assert summation(f2, (k, 1, oo)).simplify() == 2**I/(2 - 2**I)
     assert (summation(f2, (k, 1, x)).simplify() ==
             2**(-x + I)*(-2**x + 2**(I*x))/(-2 + 2**I))
+
+
+def test_sympyissue_21651():
+    a = Sum(floor(2*2**(-n)), (n, 1, 2))
+    b = floor(2*2**(-1)) + floor(2*2**(-2))
+
+    assert a.doit() == b.doit()
diff --git a/docs/release/notes-0.13.rst b/docs/release/notes-0.13.rst
@@ -97,3 +97,4 @@ These Sympy issues also were addressed:
 * :sympyissue:`9127`: ntheory.AskEvenHandler.Mul is order-dependent
 * :sympyissue:`21606`: Notimplemented in simple limit
 * :sympyissue:`21641`: Simplify hangs
+* :sympyissue:`21651`: doit() method *sometimes* ignores floor and ceiling within Sum