Re: Help with bit bashing code: differences between C and CL

Hi

Thanks Pascal.

For LW on Intel (Mac) the ULP seems the same. With SBCL you should actually be able to peek at the actual bits making up the double float. Can you do something similar with LM?

Just curious: has anybody tried this on a M*/Arm Mac? Or, with LW, on your smartphone? :)

Cheers

MA

On Fri, Nov 10, 2023 at 8:29 AM Pascal Bourguignon (as pjb at informatimago dot com) lisp-hug@lispworks.com wrote:

On 9 Nov 2023, at 21:21, Marco Antoniotti marco.antoniotti@unimib.it wrote:

<problem-loop.lisp>

From the start, it looks like the ulp is more precise in C:

sbcl: 2.220446049250313d-16 clang: 2.2204460492503130808e-16

(using %.20g instead of %.20f)

Or perhaps it’s only the display procedure that truncates in lisp?

-- __Pascal J. Bourguignon__