[cfarm-users] cfarm26 FP inaccuracies

[Martin Guy]

On 8/30/26 2:29 AM, Jacob Bachmeyer wrote:
 > Paranoia's page 4 (when run on cfarm26) mentions:
 >
 >     Some subexpressions appear to be calculated extra
 >     precisely with about 11 extra B-digits, i.e.
 >     roughly 3.31133 extra significant decimals.
 >     That feature is not tested further by this program.
 >
 >
> about 11 extra bits would 
> be consistent with the x87 80-bit format vs. standard 64-bit double...
Well spotted! I bet that's it as the differences were microscopic.
So it's calculating intermediate results with too much precision for the 
IEEE. I'm not sure that's a defect!

As to why... Debian's default CFLAGS for bookworm are

     -g -O2 -ffile-prefix-map=/home/user=. -fstack-protector-strong 
-Wformat -Werror=format-security

while Alpine's are

     -Os -fstack-clash-protection -Wformat -Werror=format-security

so it's not that.