[3.13] gh-141004: Document Py_HUGE_VAL/IS_FINITE/IS_INFINITE/IS_NAN (GH-141544) (#141700)

(cherry picked from commit 630cd37)

Co-authored-by: Victor Stinner <vstinner@python.org>
Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>

Author: 3 people

Doc/c-api/float.rst

@@ -96,6 +96,14 @@ Floating-Point Objects
    the C11 standard ``<math.h>`` header.
 
 
+.. c:macro:: Py_HUGE_VAL
+
+   Equivalent to :c:macro:`!INFINITY`.
+
+   .. deprecated:: 3.14
+      The macro is :term:`soft deprecated`.
+
+
 .. c:macro:: Py_MATH_E
 
    The definition (accurate for a :c:expr:`double` type) of the :data:`math.e` constant.
@@ -140,6 +148,34 @@ Floating-Point Objects
       return PyFloat_FromDouble(copysign(INFINITY, sign));
 
 
+.. c:macro:: Py_IS_FINITE(X)
+
+   Return ``1`` if the given floating-point number *X* is finite,
+   that is, it is normal, subnormal or zero, but not infinite or NaN.
+   Return ``0`` otherwise.
+
+   .. deprecated:: 3.14
+      The macro is :term:`soft deprecated`.  Use :c:macro:`!isfinite` instead.
+
+
+.. c:macro:: Py_IS_INFINITY(X)
+
+   Return ``1`` if the given floating-point number *X* is positive or negative
+   infinity.  Return ``0`` otherwise.
+
+   .. deprecated:: 3.14
+      The macro is :term:`soft deprecated`.  Use :c:macro:`!isinf` instead.
+
+
+.. c:macro:: Py_IS_NAN(X)
+
+   Return ``1`` if the given floating-point number *X* is a not-a-number (NaN)
+   value.  Return ``0`` otherwise.
+
+   .. deprecated:: 3.14
+      The macro is :term:`soft deprecated`.  Use :c:macro:`!isnan` instead.
+
+
 Pack and Unpack functions
 -------------------------