On Fri, 1 Sept 2023 at 10:57, Mathieu Malaterre via Gcc-help <gcc-help@xxxxxxxxxxx> wrote: > > Hi all, > > I am reading a previous post from Pascal Cuoq(*), and it seems things > have changed quite a bit in GCC nowadays. I fail to understand how > FLT_EVAL_METHOD relates to fexcess-precision. Did I miss something? See https://gcc.gnu.org/gcc-13/changes.html#cxx > > --- > > Here is what I see on my Debian/sid/i386 system: > > % gcc -O2 -fexcess-precision=fast m.c && ./a.out > float eps = 1.192093e-07 > 2 > > while: > > % gcc -O2 -fexcess-precision=standard m.c && ./a.out > float eps = 1.084202e-19 > 2 > > with: > > % cat m.c > #include <stdio.h> > #include <float.h> > > int main(void) > { > float floatEps = 1; > > while (1 + floatEps / 2 != 1) > floatEps /= 2; > > printf("float eps = %e\n", floatEps); > printf("%d\n", FLT_EVAL_METHOD); > } > > For reference: > > % gcc --version > gcc (Debian 13.2.0-2) 13.2.0 > > (*) https://stackoverflow.com/a/16064515/136285 > -- > Mathieu
