From:

Date:

April 24, 2015 13:29Subject:

Re: [perl #124382] [PATCH] Speed up Math::BigFloat -> blog().Message ID:

CAATnKFDKkr9-foyphi+_qZAUJfk6yG9cNv-VOO_BU1ViWvtajg@mail.gmail.comOn 25 April 2015 at 01:16, Peter J. Acklam via RT <perlbug-followup@perl.org > wrote: > # New Ticket Created by (Peter J. Acklam) > # Please include the string: [perl #124382] > # in the subject line of all future correspondence about this issue. > # <URL: https://rt.perl.org/Ticket/Display.html?id=124382 > > > > Speed up Math::BigFloat -> blog(). > > - Intermediate computations in blog() increases the number of digits > significantly in some cases. Reduce the number of digits by rounding. > However, keep some extra digits for remaining intermediate computations > before the final rounding. > > - This patch fixes CPAN RT #43924. > >From a6be9fcc4d8599540a1ec04fd04f8d9d0672cad0 Mon Sep 17 00:00:00 2001 > From: Peter John Acklam <pjacklam@online.no> > Date: Fri, 24 Apr 2015 15:13:33 +0200 > Subject: [PATCH] Speed up Math::BigFloat -> blog(). > > - Intermediate computations in blog() increases the number of digits > significantly in some cases. Reduce the number of digits by rounding. > However, keep some extra digits for remaining intermediate computations > before the final rounding. > > - This patch fixes CPAN RT #43924. > --- > dist/Math-BigInt/lib/Math/BigFloat.pm | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/dist/Math-BigInt/lib/Math/BigFloat.pm > b/dist/Math-BigInt/lib/Math/BigFloat.pm > index 1c31496..3c51914 100644 > --- a/dist/Math-BigInt/lib/Math/BigFloat.pm > +++ b/dist/Math-BigInt/lib/Math/BigFloat.pm > @@ -1476,6 +1476,7 @@ sub _log_10 > { > $twos++; $x->bdiv($two,$scale+4); # keep all digits > } > + $x->bround($scale+4); > # $twos > 0 => did mul 2, < 0 => did div 2 (but we never did both) > # So calculate correction factor based on ln(2): > if ($twos != 0) > -- > 2.1.4 > > > Q) Does this affect the overall precision of the floating point math? I am ignorant of the internals, but that sort of concern seems to be the sort of thing lay-folk who are simply using the library would care about, and so I'm just looking for some kind of assurance the rounding is not *premature* rounding. -- Kent *KENTNL* - https://metacpan.org/author/KENTNLThread Previous

- [perl #124382] [PATCH] Speed up Math::BigFloat -> blog(). by perlbug-followup
**Re: [perl #124382] [PATCH] Speed up Math::BigFloat -> blog().**by Kent Fredric

nntp.perl.org: Perl Programming lists via nntp and http.

Comments to Ask Bjørn Hansen at ask@perl.org | Group listing | About