develooper Front page | perl.perl5.porters | Postings from January 2012

[perl #107700] Re: [OTS#020287925] Rounding error in sprintf.

From:
support
Date:
January 6, 2012 18:13
Subject:
[perl #107700] Re: [OTS#020287925] Rounding error in sprintf.
Message ID:
rt-3.6.HEAD-14510-1325898165-1938.107700-75-0@perl.org
# New Ticket Created by  support 
# Please include the string:  [perl #107700]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=107700 >


sdd@google.com,

Behaviour of sprintf() is dependent on the underlying C libraries. See these
discussions:
http://stackoverflow.com/questions/1651671/why-does-perls-sprintf-not-round-floating-point-numbers-correctly

http://perldoc.perl.org/perlfaq4.html#Does-Perl-have-a-round%28%29-function%3f--What-about-ceil%28%29-and-floor%28%29%3f--Trig-functions%3f

Best regards,

Graham Stuart
Technical Support Engineer
ActiveState - The Dynamic Language Experts
http://www.ActiveState.com
Get insights on Open Source and Dynamic Languages at www.activestate.com/blog

01/06/2012 11:20 - sdd@google.com wrote:

> 
> This is a bug report for perl from sdd@google.com,
> generated with the help of perlbug 1.39 running under perl 5.14.2.
> 
> 
> -----------------------------------------------------------------
> [Please describe your issue here]
> 
> Using ActivePerl 5.14.2, and at various other versions going as far back as the
5.8.9 version shipped with Leopard, the following command returns what I believe
to be an incorrect result:
> 
> bash-3.2$ ./perl -e 'print sprintf("%d\n", "2.47" * 100);'
> 246
> bash-3.2$ 
> 
> 
> 
> [Please do not change anything below this line]
> -----------------------------------------------------------------
> ---
> Flags:
>     category=core
>     severity=medium
> ---
> Site configuration information for perl 5.14.2:
> 
> Configured by ActiveState at Fri Oct  7 15:56:08 PDT 2011.
> 
> Summary of my perl5 (revision 5 version 14 subversion 2) configuration:
>    
>   Platform:
>     osname=darwin, osvers=9.8.0, archname=darwin-thread-multi-2level
>     uname='darwin kitty 9.8.0 darwin kernel version 9.8.0: wed jul 15 16:55:01
pdt 2009; root:xnu-1228.15.4~1release_i386 i386 '
>     config_args='-ders -Dcc=gcc -Dusethreads -Duseithreads -Uinstallusrbinperl
-Ulocincpth= -Uloclibpth= -Ud_poll -Ui_poll -Ui_libutil
-Aldflags=-Wl,-search_paths_first -Alddlflags=-Wl,-search_paths_first
-Accflags=-arch i386 -arch x86_64 -Aldflags=-arch i386 -arch x86_64
-Alddlflags=-arch i386 -arch x86_64 -Accflags=-nostdinc
-B/Developer/SDKs/MacOSX10.5.sdk/usr/include/gcc
-B/Developer/SDKs/MacOSX10.5.sdk/usr/lib/gcc
-isystem/Developer/SDKs/MacOSX10.5.sdk/usr/include
-F/Developer/SDKs/MacOSX10.5.sdk/System/Library/Frameworks
-mmacosx-version-min=10.5 -Aldflags=-Wl,-syslibroot,/Developer/SDKs/MacOSX10.5.sdk
-mmacosx-version-min=10.5
-Alddlflags=-Wl,-syslibroot,/Developer/SDKs/MacOSX10.5.sdk
-mmacosx-version-min=10.5 -Accflags=-DUSE_SITECUSTOMIZE -Duselargefiles
-Accflags=-DPERL_RELOCATABLE_INCPUSH -Accflags=-fno-merge-constants
-Dprefix=/usr/local/ActivePerl-5.14 -Dprivlib=/usr/local/ActivePerl-5.14/lib
-Darchlib=/usr/local/ActivePerl-5.14/lib -Dsiteprefix=/usr/local/ActiveP
>  erl-5.14/site -Dsitelib=/usr/local/ActivePerl-5.14/site/lib
-Dsitearch=/usr/local/ActivePerl-5.14/site/lib -Dsed=/usr/bin/sed -Duseshrplib
-Dcf_by=ActiveState -Dcf_email=support@ActiveState.com'
>     hint=recommended, useposix=true, d_sigaction=define
>     useithreads=define, usemultiplicity=define
>     useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
>     use64bitint=define, use64bitall=define, uselongdouble=undef
>     usemymalloc=n, bincompat5005=undef
>   Compiler:
>     cc='gcc', ccflags ='-fno-common -DPERL_DARWIN -arch i386 -DUSE_SITECUSTOMIZE
-DPERL_RELOCATABLE_INCPUSH -fno-merge-constants -fno-strict-aliasing -pipe
-fstack-protector',
>     optimize='-O3',
>     cppflags='-no-cpp-precomp -fno-common -DPERL_DARWIN -no-cpp-precomp -arch
i386 -nostdinc -B/Developer/SDKs/MacOSX10.5.sdk/usr/include/gcc
-B/Developer/SDKs/MacOSX10.5.sdk/usr/lib/gcc
-isystem/Developer/SDKs/MacOSX10.5.sdk/usr/include
-F/Developer/SDKs/MacOSX10.5.sdk/System/Library/Frameworks
-mmacosx-version-min=10.5 -DUSE_SITECUSTOMIZE -DPERL_RELOCATABLE_INCPUSH
-fno-merge-constants -fno-strict-aliasing -pipe -fstack-protector'
>     ccversion='', gccversion='i686-apple-darwin10-llvm-gcc-4.2 (GCC) 4.2.1
(Based on Apple Inc. build 5658) (LLVM build 2336.1.00)', gccosandvers=''
>     intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
>     d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
>     ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
>     alignbytes=8, prototype=define
>   Linker and Libraries:
>     ld='cc -mmacosx-version-min=10.5', ldflags =' -Wl,-search_paths_first -arch
i386 -fstack-protector'
>     libpth=/lib /usr/lib /usr/local/lib
>     libs=-ldbm -ldl -lm -lutil -lc
>     perllibs=-ldl -lm -lutil -lc
>     libc=, so=dylib, useshrplib=true, libperl=libperl.dylib
>     gnulibc_version=''
>   Dynamic Linking:
>     dlsrc=dl_dlopen.xs, dlext=bundle, d_dlsymun=undef, ccdlflags=' '
>     cccdlflags=' ', lddlflags=' -bundle -undefined dynamic_lookup
-Wl,-search_paths_first -arch i386 -fstack-protector'
> 
> Locally applied patches:
>     ACTIVEPERL_LOCAL_PATCHES_ENTRY
> 
> ---
> @INC for perl 5.14.2:
>     /Users/sdd/Library/ActivePerl-5.14/lib
>     /usr/local/ActivePerl-5.14/site/lib
>     /usr/local/ActivePerl-5.14/lib
>     .
> 
> ---
> Environment for perl 5.14.2:
>     DYLD_LIBRARY_PATH (unset)
>     HOME=/Users/sdd
>     LANG (unset)
>     LANGUAGE (unset)
>     LD_LIBRARY_PATH (unset)
>     LOGDIR (unset)
>    
PATH=/Users/sdd/.config-dir/bin:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/opt/X11/bin:/usr/local/bin/g4bin:/usr/local/sbin:/usr/X11/bin:/opt/X11/bin
>     PERL_BADLANG (unset)
>     SHELL=/bin/bash
> 




nntp.perl.org: Perl Programming lists via nntp and http.
Comments to Ask Bjørn Hansen at ask@perl.org | Group listing | About