https://github.com/python/cpython/commit/22f8e430f81b8b8966bff0efe65786515a132b7e commit: 22f8e430f81b8b8966bff0efe65786515a132b7e branch: 3.12 author: Miss Islington (bot) <[email protected]> committer: Yhg1s <[email protected]> date: 2024-12-02T14:52:49+01:00 summary:
[3.12] gh-99880: document rounding mode for new-style formatting (GH-121481) (#126335) The CPython uses _Py_dg_dtoa(), which does rounding to nearest with half to even tie-breaking rule. If that functions is unavailable, PyOS_double_to_string() fallbacks to system snprintf(). Since CPython 3.12, build requirements include C11 compiler *and* support for IEEE 754 floating point numbers (Annex F). This means that FE_TONEAREST macro is available and, per default, printf-like functions should use same rounding mode as _Py_dg_dtoa(). (cherry picked from commit 7d7d56d8b1147a6b85e1c09d01b164df7c5c4942) Co-authored-by: Sergey B Kirpichev <[email protected]> Co-authored-by: Bénédikt Tran <[email protected]> files: M Doc/library/string.rst diff --git a/Doc/library/string.rst b/Doc/library/string.rst index 9e8e44a8abe770..a000bb49f14800 100644 --- a/Doc/library/string.rst +++ b/Doc/library/string.rst @@ -589,6 +589,11 @@ The available presentation types for :class:`float` and | | as altered by the other format modifiers. | +---------+----------------------------------------------------------+ +The result should be correctly rounded to a given precision ``p`` of digits +after the decimal point. The rounding mode for :class:`float` matches that +of the :func:`round` builtin. For :class:`~decimal.Decimal`, the rounding +mode of the current :ref:`context <decimal-context>` will be used. + The available presentation types for :class:`complex` are the same as those for :class:`float` (``'%'`` is not allowed). Both the real and imaginary components of a complex number are formatted as floating-point numbers, according to the _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3/lists/python-checkins.python.org/ Member address: [email protected]
