Update whats_new to be more vocal about mathtext.default settings

llohse · llohse · commit 2016c6e9985d · 2026-02-26T09:56:32.000+01:00
diff --git a/doc/release/next_whats_new/mathnormal.rst b/doc/release/next_whats_new/mathnormal.rst
@@ -2,7 +2,9 @@ Mathtext distinguishes *italic* and *normal* font
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 Matplotlib's lightweight TeX expression parser (``usetex=False``) now distinguishes between *italic* and *normal* math fonts to closer replicate the behaviour of LaTeX.
-Italic font is selected with ``\mathit``,  whereas the normal math font is selected by default in math environment but can be explicitly set with the new ``\mathnormal`` command.
+The normal math font is selected by default in math environment (unless the rcParam ``mathtext.default`` is overwritten) but can be explicitly set with the new ``\mathnormal`` command. Italic font is selected with ``\mathit``.
 The main difference is that *italic* produces italic digits, whereas *normal* produces upright digits. Previously, it was not possible to typeset italic digits.
+Note that ``normal`` now corresponds to what used to be ``it``, whereas ``it`` now renders all characters italic.
+**Important**: In case the default mathematics font is overwritten by setting ``mathtext.default: it`` in ``matplotlibrc``, it must be either commented out or changed to ``mathtext.default: normal`` to preserve its behaviour. Otherwise, all alphanumeric characters, including digits, are rendered italic. 
 
 One difference to traditional LaTeX is that LaTeX further distinguishes between *normal* (``\mathnormal``) and *default math*, where the default uses roman digits and normal uses oldstyle digits. This distinction is no longer present with modern LaTeX engines and unicode-math nor in Matplotlib.
