Am 20.04.2011 15:04, schrieb Hans-Peter Diettrich: > Florian Klämpfl schrieb: >> Am 20.04.2011 00:05, schrieb Hans-Peter Diettrich: >>> Florian Klaempfl schrieb: >>> >>>> Using extended typically hides only bad numerical algorithms. There >>>> might be some corner cases where extended is usefull but I general I >>>> think it's a matter of bad algorithms. >>> Some algorithms convert faster with increased accuracy. >> >> I guess you meant converge? > > Right. I had a phone call just while answering :-( > >> This might be true, but processing of >> extended types is also slower: the memory footprint increases and even >> worse, extended arrays are typically aligned to 4 or even 16 byte >> borders so they take 12 or 16 byte in memory. > > Please don't mix up the internal processing and the external storage of > the values. Type coercion (expansion) is frequently used in the > evaluation of expressions, be inside a GPU or FPU.
Actually, this is even another problem of the x87 fpu: expressions are often evaluted more precisely than required thus resulting in unpredicatable results because it depends on the compiler if it stores a temp. value during evaluation of an expression in memory or not. The correct solution to round after each operation is too slow, everything else is unpredictable. _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
