Hi - We noticed some code was very slow in gfortran vs g77, almost a factor
of 7 times slower. This appears to be because gfortran uses the expf
liubrary function call for the fortran exp() function for single precision
numbers, but g77 uses the exp library function (i.e. the double precision
f
Hi Jeremy,
-- it's unarguably a glibc issue: if exp() is fast and expf() is
slow, why doesn't glibc implement expf() by calling exp()? (yes, there
can be other issues like rounding or so, but they can also be dealt
with separately)
-- a similar bug was already reported a year and a half
On 09/04/2009 05:04 PM, FX wrote:
> -- it's unarguably a glibc issue: if exp() is fast and expf() is
> slow, why doesn't glibc implement expf() by calling exp()? (yes, there
> can be other issues like rounding or so, but they can also be dealt
> with separately)
If I recall correctly, it is most
> "Jeremy" == Jeremy Sanders writes:
Jeremy> You can see the very large speed differences by telling gfortran
Jeremy> to always use double precision numbers.
Jeremy> This can be replicated with this simple program:
Jeremy> Compiled with gfortran -O2:
Jeremy> real0m29.921s
Jeremy> user
