Merge pull request #1293 from skirpichev/fix-1262

series: correct branch handling for log()
diofant · Feb 21, 2023 · ca1af5c · ca1af5c
2 parents da60cc8 + 57685c7
commit ca1af5c
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diff --git a/diofant/functions/elementary/exponential.py b/diofant/functions/elementary/exponential.py
@@ -377,6 +377,8 @@ def _eval_nseries(self, x, n, logx):
             log_series += Order(t**n, x)
             # branch handling
             if c.is_negative:
+                if t.is_Order:
+                    return self._eval_nseries(x, n + 1, logx)
                 l = floor(arg(t.removeO()*c)/(2*pi)).limit(x, 0)
                 if l.is_finite:
                     log_series += 2*I*pi*l

diff --git a/diofant/tests/calculus/test_limits.py b/diofant/tests/calculus/test_limits.py
@@ -170,6 +170,9 @@ def test_basic6():
     assert limit(log(1/x) + 1/sin(x), x, 0) == oo
     assert limit(log(1/x) + 1/x, x, 0) == oo
 
+    # issue diofant/diofant#1262
+    assert limit(I*exp(I*x)*log(exp(I*x)), x, -pi) == -pi
+
 
 def test_sympyissue_3885():
     assert limit(x*y + x*z, z, 2) == x*y + 2*x