On Thu, Mar 06, 2008, Colin Percival wrote: > David Schultz wrote: > > On Thu, Mar 06, 2008, Colin Percival wrote: > >> explicit or implicit final destination. When a variable with a declared > >> format > >> > >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > >> is a final destination, as in format conversion to a variable, that > >> declared > >> > >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > >> format of that variable governs its rounding. The format of an implicit > >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > >> destination, or of an explicit destination without a declared format, is > >> defined by language standard expression evaluation rules. > > > > I think you missed the point about implicit destinations. > > No. Another quote: > 2.2.14 destination: The location for the result of an operation upon one or > more operands. A destination might be either explicitly designated by the > user > or implicitly supplied by the system (for example, intermediate results in > subexpressions or arguments for procedures). [...] > > Implicit destinations are things like the (x * y) in "x * y - 1.0" or in > "sqrt(x * y)". > > > The register is an implicit destination. IEEE 754R explains this > > in more detail. > > Really? I can't find any such statements... quite the contrary.
When reading the above quotation, you need to keep in mind that in their terminology, 'z = x + y' is an expression and 'x + y' is a subexpression. What you're claiming doesn't even make sense. With your rules, the 'x * y' in 'k = x * y - 1.0' could be evaluated with extra precision, the '- 1.0' would be forced to machine precision, and you'd still have double rounding on the multiply. This really *isn't* what they meant. Look, please have a careful look at section 10.2. This is a really busy week for me, and I don't have the inclination to continue this discussion if you keep sniping. _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/cvs-all To unsubscribe, send any mail to "[EMAIL PROTECTED]"
