Merge branch 'master' into constant-method-option

Author: rocky

mathics/builtin/calculus.py

@@ -369,7 +369,7 @@ class Integrate(SympyFunction):
 
     Integration in TeX:
     >> Integrate[f[x], {x, a, b}] // TeXForm
-     = \int_a^bf\left[x\right] \, dx
+     = \int_a^b f\left[x\right] \, dx
 
     #> DownValues[Integrate]
      = {}
@@ -437,12 +437,12 @@ class Integrate(SympyFunction):
         'Integrate[list_List, x_]': 'Integrate[#, x]& /@ list',
 
         'MakeBoxes[Integrate[f_, x_], form:StandardForm|TraditionalForm]':
-        r'''RowBox[{"\[Integral]", MakeBoxes[f, form], "\[InvisibleTimes]",
+        r'''RowBox[{"\[Integral]","\[InvisibleTimes]", MakeBoxes[f, form], "\[InvisibleTimes]",
                 RowBox[{"\[DifferentialD]", MakeBoxes[x, form]}]}]''',
         'MakeBoxes[Integrate[f_, {x_, a_, b_}], '
         'form:StandardForm|TraditionalForm]':
         r'''RowBox[{SubsuperscriptBox["\[Integral]", MakeBoxes[a, form],
-                MakeBoxes[b, form]], MakeBoxes[f, form], "\[InvisibleTimes]",
+                MakeBoxes[b, form]], "\[InvisibleTimes]" , MakeBoxes[f, form], "\[InvisibleTimes]",
                 RowBox[{"\[DifferentialD]", MakeBoxes[x, form]}]}]''',
     }
 

mathics/builtin/system.py

@@ -408,9 +408,11 @@ class UserName(Predefined):
 
     def evaluate(self, evaluation) -> String:
         try:
-            return String(os.getlogin())
+            user = os.getlogin()
         except:
-            return String("??user-retrieval-error")
+            import pwd
+            user = pwd.getpwuid(os.getuid())[0]
+        return String(user)
 
 
 class Version(Predefined):

mathics/core/expression.py

@@ -2137,7 +2137,7 @@ def __neg__(self) -> 'Rational':
 
     @property
     def is_zero(self) -> bool:
-        return self.numerator().is_zero and not self.denominator().is_zero()
+        return self.numerator().is_zero # (implicit) and not (self.denominator().is_zero)
 
 
 class Real(Number):