| Subject: | Mixed < fails after abs (ditto for >) |
For some pairs of operands of which exactly one is a PARI float, the >, >=, <, and <= operations fail after one applies abs to the PARI operand. The following short program illustrates the problem. Note that, that after the call to abs, the expressions 1E-17 > 0.1 and 1E-17 >= 0.1 evaluate to true, while 1E-17 < 0.1 and 1E-17 <= 0.1 evaluate to false. Also note that these operations work correctly before the call to abs.
=========================================================================
use strict;
use warnings;
use Math::Pari;
my $x = PARI( 1E-17 );
my $y = 1E-01;
printf "x: $x is a << %s >>\n", ref $x;
printf "y: $y is a << %s >>\n", ref $y;
printf "x < y = %d\n", $x < $y;
printf "x <= y = %d\n", $x <= $y;
printf "x > y = %d\n", $x > $y;
printf "x >= y = %d\n", $x >= $y;
printf "x == y = %d\n", $x == $y;
print "\n";
{ my $z = abs( $y ); }
printf "x: $x is a << %s >>\n", ref $x;
printf "y: $y is a << %s >>\n", ref $y;
printf "x < y = %d\n", $x < $y;
printf "x <= y = %d\n", $x <= $y;
printf "x > y = %d\n", $x > $y;
printf "x >= y = %d\n", $x >= $y;
printf "x == y = %d\n", $x == $y;
__END__
x: 1.000000000000000071E-17 is a << Math::Pari >>
y: 0.1 is a << >>
x < y = 1
x <= y = 1
x > y = 0
x >= y = 0
x == y = 0
x: 1.000000000000000071E-17 is a << Math::Pari >>
y: 0.1 is a << >>
x < y = 0
x <= y = 0
x > y = 1
x >= y = 1
x == y = 0
=========================================================================
This is on Linux (Debian Woody). System details follow.
Site configuration information for perl v5.8.6:
Configured by kynn at Tue Apr 12 12:24:11 EDT 2005.
Summary of my perl5 (revision 5 version 8 subversion 6) configuration:
Platform:
osname=linux, osvers=2.4.18-686-smp, archname=i686-linux-ld
uname='linux luna 2.4.18-686-smp #1 smp sun apr 14 12:07:19 est 2002
i686 unknown '
config_args=''
hint=recommended, useposix=true, d_sigaction=define
usethreads=undef use5005threads=undef useithreads=undef
usemultiplicity=undef
useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
use64bitint=undef use64bitall=undef uselongdouble=define
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-fno-strict-aliasing -pipe -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2',
cppflags='-fno-strict-aliasing -pipe -I/usr/local/include'
ccversion='', gccversion='2.95.4 20011002 (Debian prerelease)',
gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='long double', nvsize=12,
Off_t='off_t', lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lnsl -lgdbm -ldbm -ldb -ldl -lm -lcrypt -lutil -lc
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
libc=/lib/libc-2.2.5.so, so=so, useshrplib=false, libperl=libperl.a
gnulibc_version='2.2.5'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'
Locally applied patches:
---
@INC for perl v5.8.6:
/home/kynn/local/lib/perl/my
/home/kynn/local/lib/perl/5.8.4
/home/kynn/local/lib/perl/5.6.1
/home/kynn/local/lib/perl5/5.8.6/i686-linux-ld
/home/kynn/local/lib/perl5/5.8.6
/home/kynn/local/lib/perl5/i686-linux-ld
/home/kynn/local/lib/perl5
/home/kynn/local/lib/perl5/5.8.6/i686-linux-ld
/home/kynn/local/lib/perl5/5.8.6
/home/kynn/local/lib/perl5/site_perl/5.8.6/i686-linux-ld
/home/kynn/local/lib/perl5/site_perl/5.8.6
/home/kynn/local/lib/perl5/site_perl
.
---
Environment for perl v5.8.6:
HOME=/home/kynn
LANG=C
LANGUAGE (unset)
LD_LIBRARY_PATH=/home/kynn/local/lib:/opt/java/jdk/lib/i386
LOGDIR (unset)
PATH=.:/home/kynn/local/bin:/home/kynn/local/usr/bin:/home/kynn/local/local/bin:/bin-
\ :/usr/bin:/usr/local/bin:/usr/X11R6/bin:/home/kynn/java/javacc/bin:/opt/java/jdk/bin-
\ :/usr/pbs/bin:/home/kynn/opt/ant/bin
PERL5LIB=/home/kynn/local/lib/perl/my:/home/kynn/local/lib/perl/5.8.4:/home/kynn/loc-
\ al/lib/perl/5.6.1:/home/kynn/local/lib/perl5
PERL5_CPANPLUS_CONFIG=/home/kynn/.cpanplus/config
PERL_BADLANG (unset)
SHELL=/usr/bin/zsh