On Sun, Aug 10, 2014 at 2:00 AM, Ulrich Drepper <drep...@gmail.com> wrote:
> On Sat, Aug 9, 2014 at 1:40 PM, Marc Glisse <marc.gli...@inria.fr> wrote:
>> __x = result_type(2.0) * __aurng() - 1.0;
>
> You're right, we of course need the negatives as well.
>
>> Assuming the 2 coordinates are obtained through a rescaling x->2*x-1, if
>> __sq is not exactly 0, it must be between 2^-103 and 1 (for ieee
>> double), so I am not sure hypot gains that much (at least in my mind
>> hypot was mostly a gain close to 0 or infinity, but maybe it has more
>> advantages). It can only hurt speed though, so not a big issue.
>
> Depending on how similar in size the two values are, not using hypot()
> can drop quite a few bits. Especially with the scaling through
> division this error can be noticeable. Better be sure. Maybe at some
> point I have time to investigate the worst case scenario for the
> numbers in question but until this shows hypot isn't needed it's best
> to leave it in.
>
> I've committed the patch.
Hi,
This causes lots of tests under libstdc++-v3/testsuite/ext/ failed on
aarch64-none-elf and arm-none-eabi with below log message.
In file included from
/home/binche01/work/oban-work/build-aarch64-none-elf/obj/gcc2/aarch64-none-elf/libstdc++-v3/include/ext/random:3494:0,
from
/home/binche01/work/oban-work/src/gcc/libstdc++-v3/testsuite/ext/random/arcsine_distribution/cons/default.cc:23:
/home/binche01/work/oban-work/src/gcc/libstdc++-v3/include/ext/random.tcc:
In member function
'__gnu_cxx::{anonymous}::uniform_on_sphere_helper<2ul,
_RealType>::result_type
__gnu_cxx::{anonymous}::uniform_on_sphere_helper<2ul,
_RealType>::operator()(_NormalDistribution&,
_UniformRandomNumberGenerator&)':
/home/binche01/work/oban-work/src/gcc/libstdc++-v3/include/ext/random.tcc:1609:18:
error: 'hypot' is not a member of 'std'
auto __norm = std::hypot(__ret[0], __ret[1]);
^
/home/binche01/work/oban-work/src/gcc/libstdc++-v3/include/ext/random.tcc:1609:18:
note: suggested alternative:
In file included from
/home/binche01/work/oban-work/build-aarch64-none-elf/obj/gcc2/aarch64-none-elf/libstdc++-v3/include/cmath:44:0,
from
/home/binche01/work/oban-work/build-aarch64-none-elf/obj/gcc2/aarch64-none-elf/libstdc++-v3/include/random:38,
from
/home/binche01/work/oban-work/build-aarch64-none-elf/obj/gcc2/aarch64-none-elf/libstdc++-v3/include/ext/random:38,
from
/home/binche01/work/oban-work/src/gcc/libstdc++-v3/testsuite/ext/random/arcsine_distribution/cons/default.cc:23:
/home/binche01/work/oban-work/target-aarch64-none-elf/aarch64-none-elf/include/math.h:306:15:
note: 'hypot'
extern double hypot _PARAMS((double, double));
^
FAIL: ext/random/arcsine_distribution/cons/default.cc (test for excess errors)
Excess errors:
/home/binche01/work/oban-work/src/gcc/libstdc++-v3/include/ext/random.tcc:1609:18:
error: 'hypot' is not a member of 'std'
Thanks,
bin
