Turn negative zero into positive zero in pdg_format (#916)

Closes #840 (hopefully)

Negative "-0" is turned into "0" by pdg_format.

src/iminuit/pdg_format.py

@@ -180,6 +180,9 @@ def _strip(items: List[str]) -> List[str]:
         if i > 0:
             for k in mask:
                 items[k] = items[k][:-i]
+        # turn negative zero into positive zero
+        if items[0] == "-0":
+            items[0] = "0"
     return items
 
 

tests/test_pdg_format.py

@@ -81,6 +81,8 @@ def test_strip():
     assert _strip(["0.11", "0.20"]) == ["0.11", "0.20"]
     assert _strip(["10.0", "20.0"]) == ["10", "20"]
     assert _strip(["1.200", "3.40"]) == ["1.20", "3.4"]
+    assert _strip(["0.000", "0.000"]) == ["0", "0"]
+    assert _strip(["-0.00", "0.00"]) == ["0", "0"]
 
 
 def test_term_format():

tests/test_tabulate.py

@@ -33,7 +33,7 @@ def test_matrix():
         == """
       x    y
 --  ---  ---
-x     1   -0
-y    -0    4
+x     1    0
+y     0    4
 """
     )