modulus redux

[Andrei Alexandrescu]

Ok, here's how I rewrote the section on multiplicative operations. The 
text is hardly intelligible due to all formatting, sorry about that (but 
it looks much better in a specialized editor). Comments and suggestions 
welcome.

\subsection{Multiplicative Expressions}

The  multiplicative expressions  are multiplication  (\ccbox{a  * b}),
division  (\ccbox{a  / b}),  and  remainder  (\ccbox{a  \% b}).   They
operate  on numeric types  only. The  result type  of either  of these
operations   is  same  as   the  type   of  \ccbox{true   ?  a   :  b}
(see~\S~\ref{sec:conditional-operator}).

If~@b@ is zero in the integral  operation \ccbox{a / b} or \ccbox{a \%
    b}, a hardware  exception is thrown. If the  division would yield a
fractional number,  it is always truncated towards  zero (for example,
\ccbox{7  /  3}  yields~@2@  and  \ccbox{-7 /  3}  yields~@-2@).   The
expression \ccbox{a \% b} is defined such  that \cc{a == (a / b) * b +
    a  \%  b},  so  \ccbox{7  \%  3}  yields~@1@  and  \ccbox{-7  /  3}
yields~@-1 at .

\dee also  defines modulus for floating-point  numbers. The definition
is more involved. When at least one of @a@ and @b@ is a floating-point
value in  \cc{a \% b}, the  result is the largest  (in absolute value)
floating-point number @r@ satisfying the following conditions:

\begin{itemize*}
\item @a@ and @r@ do not have opposite signs;
\item  @r@ is  smaller than  @b@  in absolute  value, \ccbox{abs(r)  <
      abs(b)};
\item there exists a number @q@ of type @long@ such that \ccbox{r == a
      - q * b}.
\end{itemize*}

If such  a number  cannot be found,  \ccbox{a \%  b} yields the  Not A
Number (NaN) special value.


Andrei