Update of /cvsroot/python/python/dist/src/Doc/lib In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv20564 Modified Files: Tag: release24-maint libdecimal.tex Log Message: More info on rounding modes. Add sections for floating point notes. Index: libdecimal.tex =================================================================== RCS file: /cvsroot/python/python/dist/src/Doc/lib/libdecimal.tex,v retrieving revision 1.24.2.2 retrieving revision 1.24.2.3 diff -u -d -r1.24.2.2 -r1.24.2.3 --- libdecimal.tex 15 Jun 2005 16:54:30 -0000 1.24.2.2 +++ libdecimal.tex 1 Jul 2005 16:56:53 -0000 1.24.2.3 @@ -501,13 +501,15 @@ arithmetic operations in the context. The \var{rounding} option is one of: - \constant{ROUND_CEILING} (towards \constant{Infinity}), - \constant{ROUND_DOWN} (towards zero), - \constant{ROUND_FLOOR} (towards \constant{-Infinity}), - \constant{ROUND_HALF_DOWN} (towards zero), - \constant{ROUND_HALF_EVEN}, - \constant{ROUND_HALF_UP} (away from zero), or - \constant{ROUND_UP} (away from zero). + \begin{itemize} + \item \constant{ROUND_CEILING} (towards \constant{Infinity}), + \item \constant{ROUND_DOWN} (towards zero), + \item \constant{ROUND_FLOOR} (towards \constant{-Infinity}), + \item \constant{ROUND_HALF_DOWN} (to nearest with ties going towards zero), + \item \constant{ROUND_HALF_EVEN} (to nearest with ties going to nearest even integer), + \item \constant{ROUND_HALF_UP} (to nearest with ties going away from zero), or + \item \constant{ROUND_UP} (away from zero). + \end{itemize} The \var{traps} and \var{flags} fields list any signals to be set. Generally, new contexts should only set traps and leave the flags clear. @@ -834,6 +836,8 @@ %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \subsection{Floating Point Notes \label{decimal-notes}} +\subsubsection{Mitigating round-off error with increased precision} + The use of decimal floating point eliminates decimal representation error (making it possible to represent \constant{0.1} exactly); however, some operations can still incur round-off error when non-zero digits exceed the @@ -881,6 +885,7 @@ Decimal("0.0060000") \end{verbatim} +\subsubsection{Special values} The number system for the \module{decimal} module provides special values including \constant{NaN}, \constant{sNaN}, \constant{-Infinity},