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sprintf partial at rounding #914

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p5pRT opened this issue Dec 3, 1999 · 2 comments
Closed

sprintf partial at rounding #914

p5pRT opened this issue Dec 3, 1999 · 2 comments
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distro-Solaris documentation

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@p5pRT
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p5pRT commented Dec 3, 1999

Migrated from rt.perl.org#1850 (status was 'resolved')

Searchable as RT1850$
@p5pRT
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p5pRT commented Dec 3, 1999

From aam@astro.caltech.edu

Hi,

I came across the curious fact while using sprintf to round off
numbers that it does not like odd numbers. sprintf rounds
3.5 to 4 as it should (because 3.0 rounds off to 3)
but it also rounds off 4.5 to 4. In fact all semi-integral numbers
are rounded off to even numbers!

Here is a sample program​:

#!/usr/local/bin/perl -w
for($i=-10.5;$i<10.5;++$i){
$rounded=sprintf("%.0f",$i);
print "$rounded ";
}
print "\n";

The program prints​:

-10 -10 -8 -8 -6 -6 -4 -4 -2 -2 -0 0 2 2 4 4 6 6 8 8 10

What sprintf is doing seems very weird and would certainly need
more computation than it should be using.

I do nto think I have any solution but would appreciate one
since I presently have to do more complex things to round off
numbers​:
$i=$i-int($i)<0.5?int($i)​:1+int($i);

Cheers,
ashish mahabal
aam@​astro.caltech.edu

Perl Info 


Site configuration information for perl 5.00404:

Configured by cld at Mon Sep  7 15:53:59 PDT 1998.

Summary of my perl5 (5.0 patchlevel 4 subversion 4) configuration:
  Platform:
    osname=solaris, osvers=2.6, archname=sun4-solaris
    uname='sunos phobos 5.6 generic sun4u sparc sunw,ultra-1 '
    hint=recommended, useposix=true, d_sigaction=define
    bincompat3=y useperlio=undef d_sfio=undef
  Compiler:
    cc='gcc', optimize='-O', gccversion=2.8.1
    cppflags='-I/usr/local/include'
    ccflags ='-I/usr/local/include'
    stdchar='unsigned char', d_stdstdio=define, usevfork=false
    voidflags=15, castflags=0, d_casti32=define, d_castneg=define
    intsize=4, alignbytes=8, usemymalloc=y, prototype=define
  Linker and Libraries:
    ld='gcc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib /usr/ccs/lib
    libs=-lsocket -lnsl -ldl -lm -lc -lcrypt
    libc=/lib/libc.so, so=so
    useshrplib=false, libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags=' '
    cccdlflags='-fpic', lddlflags='-G -L/usr/local/lib'

Locally applied patches:
	


@INC for perl 5.00404:
	/usr/local/lib/perl5/sun4-solaris/5.00404
	/usr/local/lib/perl5
	/usr/local/lib/perl5/site_perl/sun4-solaris
	/usr/local/lib/perl5/site_perl
	.


Environment for perl 5.00404:
    HOME=/home/ganesha/aam
    LANG=C
    LD_LIBRARY_PATH=/usr/openwin/lib:/usr/local/lib:/usr/local/opt/SUNWspro/lib:/usr/local/pgplot:~/progs/scheme/scm/scsh-0.5.0/lib:/usr/openwin/lib:/usr/local/lib:/usr/local/opt/SUNWspro/SC4.0/lib:/usr/lib:/usr/local/iraf/iraf/lib:/usr/local/pgplot:/home/minerva/skybase3/lib:/usr/local/lib/netscape/rvplayer5.0:/home/minerva/skybase3/lib
    LOGDIR (unset)
    PATH=/usr/local/frame/bin:/usr/local/skicat/focas/bin:/usr/local/skicat/focas/bin:/home/kalypso/skicat2/bin:/usr/local/skicat/bin:/usr/local/skicat/auxiliary:/usr/openwin/bin:/opt/SUNWspro/bin:/usr/ccs/bin:/usr/sbin:/usr/dt/bin:/usr/openwin/bin:/usr/bin:/bin:/etc:/usr/local/bin:.:/usr/bin:/bin:/usr/ucb:/usr/etc:/usr/local/bin:/home/ganesha/aam/progs/scheme/scm/scsh-0.5.0/bin:/home/ganesha/aam/progs/csh:/home/galatea/sco/bin/morpho_ex:/home/ganesha/aam/dposs_bin:/home/ganesha/aam/bin:/home/ganesha/aam/progs/scheme/scm/scsh-0.5.0:/usr/sbin:/usr/ccs/bin:/opt/SUNWspro/bin:/home/minerva/skybase3/bin:/usr/local/opt/dophot:/usr/local/opt/dophot/extras:/usr/local/opt/dophot/postdaop:/home/minerva/skybase3/bin:/home/galatea/sco/bin:/home/galatea/sco/bin/dposs_ex/ex:/home/galatea/sco/bin/morpho_ex:/scr8/dposs/aam/wcs/wcstools-2.6.9/bin:.
    PERL_BADLANG (unset)
    SHELL=/usr/local/bin/tcsh

@p5pRT
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p5pRT commented Dec 3, 1999

From @tamias

On Fri, Dec 03, 1999 at 06​:36​:16PM -0800, Ashish Mahabal wrote​:

I came across the curious fact while using sprintf to round off
numbers that it does not like odd numbers. sprintf rounds
3.5 to 4 as it should (because 3.0 rounds off to 3)
but it also rounds off 4.5 to 4. In fact all semi-integral numbers
are rounded off to even numbers!

Have you come across
perldoc -q round
?

Ronald

@p5pRT p5pRT closed this as completed Nov 28, 2003
@p5pRT p5pRT mentioned this issue Oct 19, 2019
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