On 11/14/15, Ganesh Ajjanagadde <gajjanaga...@gmail.com> wrote: > It is known that the naive sqrt(x*x + y*y) approach for computing the > hypotenuse suffers from overflow and accuracy issues, see e.g > http://www.johndcook.com/blog/2010/06/02/whats-so-hard-about-finding-a-hypotenuse/. > This adds hypot support to FFmpeg, a C99 function. > > On platforms without hypot, this patch for simplicity does the naive > direct computation outlined above. Improvements can be made separately. > > Signed-off-by: Ganesh Ajjanagadde <gajjanaga...@gmail.com> > --- > configure | 2 ++ > libavutil/libm.h | 8 ++++++++ > 2 files changed, 10 insertions(+) > > diff --git a/configure b/configure > index d518b21..45df724 100755 > --- a/configure > +++ b/configure > @@ -1774,6 +1774,7 @@ MATH_FUNCS=" > exp2 > exp2f > expf > + hypot > isinf > isnan > ldexpf > @@ -5309,6 +5310,7 @@ disabled crystalhd || check_lib > libcrystalhd/libcrystalhd_if.h DtsCrystalHDVersi > > atan2f_args=2 > copysign_args=2 > +hypot_args=2 > ldexpf_args=2 > powf_args=2 > > diff --git a/libavutil/libm.h b/libavutil/libm.h > index 6c17b28..ab5df1b 100644 > --- a/libavutil/libm.h > +++ b/libavutil/libm.h > @@ -82,6 +82,14 @@ static av_always_inline float cbrtf(float x) > #define exp2f(x) ((float)exp2(x)) > #endif /* HAVE_EXP2F */ > > +#if !HAVE_HYPOT > +#undef hypot > +static av_always_inline av_const double hypot(double x, double y) > +{ > + return sqrt(x*x + y*y); > +} > +#endif /* HAVE_HYPOT */ > + > #if !HAVE_ISINF > static av_always_inline av_const int isinf(float x) > { > -- > 2.6.2 > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel >
nonsense. either do the right thing or don't touch the code. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
