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IEEE 754 should be IEEE 854; give precise reference for 

comparisons involving NaNs.
This commit is contained in:
Mark Dickinson 2008-02-07 01:42:06 +00:00
parent ff6672fda1
commit 00c2e65850
1 changed files with 6 additions and 6 deletions
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12
Doc/library/decimal.rst
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@ -1295,12 +1295,12 @@ The behavior of Python's comparison operators can be a little surprising where a
quiet or signaling :const:`NaN` always returns :const:`False` (even when doing
``Decimal('NaN')==Decimal('NaN')``), while a test for inequality always returns
:const:`True`. An attempt to compare two Decimals using any of the ``<``,
``<=``, ``>`` or ``>=`` operators will raise the
:exc:`InvalidOperation` signal if either operand is a :const:`NaN`, and return
:const:`False` if this signal is trapped. Note that the General Decimal
Arithmetic specification does not specify the behavior of direct comparisons;
these rules for comparisons involving a :const:`NaN` were taken from the IEEE
754 standard. To ensure strict standards-compliance, use the :meth:`compare`
``<=``, ``>`` or ``>=`` operators will raise the :exc:`InvalidOperation` signal
if either operand is a :const:`NaN`, and return :const:`False` if this signal is
trapped. Note that the General Decimal Arithmetic specification does not
specify the behavior of direct comparisons; these rules for comparisons
involving a :const:`NaN` were taken from the IEEE 854 standard (see Table 3 in
section 5.7). To ensure strict standards-compliance, use the :meth:`compare`
and :meth:`compare-signal` methods instead.
The signed zeros can result from calculations that underflow. They keep the sign