Do not space symbols in sub- and superscripts

oscargus · oscargus · commit cd8cfdcda3dc · 2023-06-24T15:04:41.000+02:00
diff --git a/lib/matplotlib/_mathtext.py b/lib/matplotlib/_mathtext.py
@@ -2163,9 +2163,11 @@ def symbol(self, s, loc, toks):
             # such as ${ -2}$, $ -2$, or $   -2$.
             prev_char = next((c for c in s[:loc][::-1] if c != ' '), '')
             # Binary operators at start of string should not be spaced
-            if (c in self._binary_operators and
-                    (len(s[:loc].split()) == 0 or prev_char == '{' or
-                     prev_char in self._left_delims)):
+            # Also, operators in sub- or superscripts should not be spaced
+            if (self._in_subscript_or_superscript or (
+                    c in self._binary_operators and (
+                    len(s[:loc].split()) == 0 or prev_char == '{' or
+                    prev_char in self._left_delims))):
                 return [char]
             else:
                 return [Hlist([self._make_space(0.2),
