From: Maxime Devos <maximedevos@telenet.be>
To: Panicz Maciej Godek <godek.maciek@gmail.com>,
Matt Wette <matt.wette@gmail.com>
Cc: Guile User <guile-user@gnu.org>
Subject: Re: Double-precision floating point arithmetics behaves differently in Guile and in C
Date: Sat, 16 Oct 2021 09:19:20 +0000 [thread overview]
Message-ID: <1ccca62c46bb1b150e1fdd44260fe67be3fd83d6.camel@telenet.be> (raw)
In-Reply-To: <CAMFYt2aCF1_d1gLDJuY_WShEHtqgRf7LiDKas74UFohR_Uwqhw@mail.gmail.com>
Panicz Maciej Godek schreef op ma 27-09-2021 om 16:04 [+0200]:
> niedz., 26 wrz 2021 o 21:11 Matt Wette <matt.wette@gmail.com>
> napisał(a):
>
> > Your post is a little vague. Are you comparing singular values
> > vectors
> > of A vs
> > eigenvalues, eigenvectors of A'*A ? Also, SVD is iterative and
> > different algorithms may yield
> > different results (and some of the SVD algorithms out there are not
> > great).
> > Are you using the exact same algorithm but noticing that (op x y)
> > in
> > Guile
> > behaves differently than (x op y) in C?
> >
> >
> Yes.
> I mean, I have used exactly the same algorithm (obtained by
> mechanically
> transforming the scmutils code into C), and I've been looking at its
> operation, and noticed that the results of floating point operations
> differed between Guile and C for the same input data.
If this is on x86,
https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-fexcess-precision
might be relevant.
Greetings,
Maxime.
prev parent reply other threads:[~2021-10-16 9:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-26 8:45 Double-precision floating point arithmetics behaves differently in Guile and in C Panicz Maciej Godek
2021-09-26 11:55 ` Panicz Maciej Godek
2021-09-26 13:16 ` Eli Zaretskii
2021-09-26 16:48 ` Panicz Maciej Godek
2021-09-26 12:57 ` tomas
2021-09-26 19:11 ` Matt Wette
2021-09-27 14:04 ` Panicz Maciej Godek
2021-10-16 9:19 ` Maxime Devos [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/guile/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1ccca62c46bb1b150e1fdd44260fe67be3fd83d6.camel@telenet.be \
--to=maximedevos@telenet.be \
--cc=godek.maciek@gmail.com \
--cc=guile-user@gnu.org \
--cc=matt.wette@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).