> Am 28.09.2020 um 00:32 schrieb Nikolay Nikolov via fpc-devel > <fpc-devel@lists.freepascal.org>: > > I don't have an exact answer, but I think higher precision is better, > compared to lower. You can not expect bitwise identical result, when using > floating point calculations anyway. For example AMD and Intel FPUs perform > calculations with some very slight variations, so the same calculation > doesn't always result in the same bitwise identical floating point number, > even though, they're practically really close, so it doesn't matter. I don't > know of any program that breaks e.g. on AMD FPUs, because it was designed for > Intel or vice versa. > > In theory this matters, if we implement 128-bit soft float support in the > compiler, or if we encounter an FPU that supports 128-bit floating point. The > question is whether it's safe to implement 80-bit x87 FPU floating point > support on host targets with 128-bit FPU support. I think it's safe, but I'm > not an expert on floating point.
This is way we should implement it completely in software: we get the same results on all platforms though they may deviate slightly from runtime results. > > But compile time calculations having a lower precision, compared to the > runtime precision is definitely bad. > > Nikolay > > _______________________________________________ > fpc-devel maillist - fpc-devel@lists.freepascal.org > https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
