This instance of PyTypeObject represents the Python floating-point
type. This is the same object as float in the Python layer.
Return true if its argument is a PyFloatObject or a subtype of
PyFloatObject. This function always succeeds.
Return true if its argument is a PyFloatObject, but not a subtype of
PyFloatObject. This function always succeeds.
Create a PyFloatObject object based on the string value in str, or
NULL on failure.
Create a PyFloatObject object from v, or NULL on failure.
Return a C double representation of the contents of pyfloat. If
pyfloat is not a Python floating-point object but has a __float__()
method, this method will first be called to convert pyfloat into a float.
If __float__() is not defined then it falls back to __index__().
This method returns -1.0 upon failure, so one should call
PyErr_Occurred() to check for errors.
在 3.8 版的變更: Use __index__() if available.
Return a C double representation of the contents of pyfloat, but without error checking.
Return a structseq instance which contains information about the
precision, minimum and maximum values of a float. It's a thin wrapper
around the header file float.h.
Return the maximum representable finite float DBL_MAX as C double.
Return the minimum normalized positive float DBL_MIN as C double.
The pack and unpack functions provide an efficient platform-independent way to store floating-point values as byte strings. The Pack routines produce a bytes string from a C double, and the Unpack routines produce a C double from such a bytes string. The suffix (2, 4 or 8) specifies the number of bytes in the bytes string.
On platforms that appear to use IEEE 754 formats these functions work by copying bits. On other platforms, the 2-byte format is identical to the IEEE 754 binary16 half-precision format, the 4-byte format (32-bit) is identical to the IEEE 754 binary32 single precision format, and the 8-byte format to the IEEE 754 binary64 double precision format, although the packing of INFs and NaNs (if such things exist on the platform) isn't handled correctly, and attempting to unpack a bytes string containing an IEEE INF or NaN will raise an exception.
On non-IEEE platforms with more precision, or larger dynamic range, than IEEE 754 supports, not all values can be packed; on non-IEEE platforms with less precision, or smaller dynamic range, not all values can be unpacked. What happens in such cases is partly accidental (alas).
在 3.11 版被加入.
The pack routines write 2, 4 or 8 bytes, starting at p. le is an
int argument, non-zero if you want the bytes string in little-endian
format (exponent last, at p+1, p+3, or p+6 p+7), zero if you
want big-endian format (exponent first, at p). The PY_BIG_ENDIAN
constant can be used to use the native endian: it is equal to 1 on big
endian processor, or 0 on little endian processor.
Return value: 0 if all is OK, -1 if error (and an exception is set,
most likely OverflowError).
There are two problems on non-IEEE platforms:
What this does is undefined if x is a NaN or infinity.
-0.0 和 +0.0 會產生同樣的位元組字串。
Pack a C double as the IEEE 754 binary16 half-precision format.
Pack a C double as the IEEE 754 binary32 single precision format.
Pack a C double as the IEEE 754 binary64 double precision format.
The unpack routines read 2, 4 or 8 bytes, starting at p. le is an
int argument, non-zero if the bytes string is in little-endian format
(exponent last, at p+1, p+3 or p+6 and p+7), zero if big-endian
(exponent first, at p). The PY_BIG_ENDIAN constant can be used to
use the native endian: it is equal to 1 on big endian processor, or 0
on little endian processor.
Return value: The unpacked double. On error, this is -1.0 and
PyErr_Occurred() is true (and an exception is set, most likely
OverflowError).
Note that on a non-IEEE platform this will refuse to unpack a bytes string that represents a NaN or infinity.
Unpack the IEEE 754 binary16 half-precision format as a C double.
Unpack the IEEE 754 binary32 single precision format as a C double.
Unpack the IEEE 754 binary64 double precision format as a C double.
