in reply to Re: When 1e-298L != 1e-298L
in thread When 1e-298L != 1e-298L

Interesting that there's also a discrepancy with 1e-298 on perl's (such as yours) whose nvtype is 'double'.
When I check on my 'double' build of perl 5.18.0, I also find a discrepancy.
The script I originally posted is not properly portable to 'double' builds of perl. This rendition of the script should work as intended for both nvtypes: 
#!perl -l
use warnings;
use strict;
use Config;

use Inline C => Config =>
  USING => 'ParseRegExp',
  BUILD_NOISY => 1;

use Inline C => <<'EOC';

SV * get_problem_val(long nvsize) {
  if(nvsize == 8) return newSVnv(1e-298);
  return newSVnv(1e-298L);
}

EOC

my $s = $Config{nvsize};
print "\n\$Config{nvtype}: $Config{nvtype}";
print "Different values" if 1e-298 != get_problem_val($s);

if($Config{nvsize} != 8) {
print scalar reverse unpack "b64", pack "D", 1e-298;
print scalar reverse unpack "b64", pack "D", get_problem_val($s);
}
else {
print scalar reverse unpack "b53", pack "F", 1e-298;
print scalar reverse unpack "b53", pack "F", get_problem_val($s);
}

[download]
Thanks, Ken.

Cheers,
Rob

Replies are listed 'Best First'.
Re^3: When 1e-298L != 1e-298L
by kcott (Archbishop) on Oct 25, 2013 at 02:47 UTC
    "This rendition of the script should work as intended for both nvtypes: ..."

    Here's the output from that code:

    validate Stage
Starting Build Preprocess Stage
get_maps Stage
Finished Build Preprocess Stage

Starting Build Parse Stage
Finished Build Parse Stage

Starting Build Glue 1 Stage
Finished Build Glue 1 Stage

Starting Build Glue 2 Stage
Finished Build Glue 2 Stage

Starting Build Glue 3 Stage
Finished Build Glue 3 Stage

Starting Build Compile Stage
  Starting "perl Makefile.PL" Stage
Writing Makefile for pm_example_pl_cb2d
Writing MYMETA.yml and MYMETA.json
  Finished "perl Makefile.PL" Stage

  Starting "make" Stage
/Users/ken/perl5/perlbrew/perls/perl-5.18.1t/bin/perl /Users/ken/perl5
+/perlbrew/perls/perl-5.18.1t/lib/5.18.1/ExtUtils/xsubpp  -typemap "/U
+sers/ken/perl5/perlbrew/perls/perl-5.18.1t/lib/5.18.1/ExtUtils/typema
+p"   pm_example_pl_cb2d.xs > pm_example_pl_cb2d.xsc && mv pm_example_
+pl_cb2d.xsc pm_example_pl_cb2d.c
cc -c  -I"/Users/ken/tmp" -fno-common -DPERL_DARWIN -fno-strict-aliasi
+ng -pipe -fstack-protector -I/usr/local/include -I/opt/local/include 
+-O3   -DVERSION=\"0.00\" -DXS_VERSION=\"0.00\"  "-I/Users/ken/perl5/p
+erlbrew/perls/perl-5.18.1t/lib/5.18.1/darwin-thread-multi-2level/CORE
+"   pm_example_pl_cb2d.c
Running Mkbootstrap for pm_example_pl_cb2d ()
chmod 644 pm_example_pl_cb2d.bs
rm -f blib/arch/auto/pm_example_pl_cb2d/pm_example_pl_cb2d.bundle
env MACOSX_DEPLOYMENT_TARGET=10.3 cc  -bundle -undefined dynamic_looku
+p -L/usr/local/lib -L/opt/local/lib -fstack-protector pm_example_pl_c
+b2d.o  -o blib/arch/auto/pm_example_pl_cb2d/pm_example_pl_cb2d.bundle
+     \
             \
      
chmod 755 blib/arch/auto/pm_example_pl_cb2d/pm_example_pl_cb2d.bundle
cp pm_example_pl_cb2d.bs blib/arch/auto/pm_example_pl_cb2d/pm_example_
+pl_cb2d.bs
chmod 644 blib/arch/auto/pm_example_pl_cb2d/pm_example_pl_cb2d.bs
  Finished "make" Stage

  Starting "make install" Stage
Files found in blib/arch: installing files in blib/lib into architectu
+re dependent library tree
Installing /Users/ken/tmp/_Inline/lib/auto/pm_example_pl_cb2d/pm_examp
+le_pl_cb2d.bs
Installing /Users/ken/tmp/_Inline/lib/auto/pm_example_pl_cb2d/pm_examp
+le_pl_cb2d.bundle
  Finished "make install" Stage

  Starting Cleaning Up Stage
  Finished Cleaning Up Stage

Finished Build Compile Stage


$Config{nvtype}: double
Different values
10000101111100000100011010000010100100111111000011011
10000101111100000100011010000010100100111111000011101

    [download]

    -- Ken

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