in reply to undefined value as an ARRAY

Curiously, when I run the following command-line script on my mac (to replicate the essentials of your code), the "bfac" call apparently does not return, and the process runs in a seemingly infinite loop, chewing up cpu time: 
perl -MMath::BigFloat -e '$|++;$x=Math::BigFloat->new("2.0");
print "\ncalling bpow at ",scalar(localtime)."\n";$x->bpow("128");
print "calling copy at ",scalar(localtime)."\n";$p=$x->copy();
print "calling bfac at ",scalar(localtime)."\n";$p->bfac();
print "finished at ",scalar(localtime)."\n"'

calling bpow at Wed Aug 11 21:44:28 2010
calling copy at Wed Aug 11 21:44:28 2010
calling bfac at Wed Aug 11 21:44:28 2010

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(still running an hour later... oh well, I'm just going to kill it now.) FWIW, I'm using the version that comes with "snow leopard" (osx 10.6.4): 
  This is perl, v5.10.0 built for darwin-thread-multi-2level

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When you ran your script, did it crash right away, or did it run for a long time before crashing?

(Updated my command-line script to include the (rather important) first line of the command.)

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Re^2: undefined value as an ARRAY
by oko1 (Deacon) on Aug 12, 2010 at 03:24 UTC

    I suspect you'd have to wait a bit more than an hour. Given this: 

    #!/usr/bin/perl -w
use strict;
use Benchmark qw/:all/;
use Math::BigFloat;

cmpthese(
    1, {
        '2**10' =>  sub { my $x = Math::BigFloat->new(2**10); my $prod
+uct = $x->copy(); $product->bfac(); },
        '2**11' =>  sub { my $x = Math::BigFloat->new(2**11); my $prod
+uct = $x->copy(); $product->bfac(); },
        '2**12' =>  sub { my $x = Math::BigFloat->new(2**12); my $prod
+uct = $x->copy(); $product->bfac(); },
        '2**13' =>  sub { my $x = Math::BigFloat->new(2**13); my $prod
+uct = $x->copy(); $product->bfac(); },
        '2**14' =>  sub { my $x = Math::BigFloat->new(2**14); my $prod
+uct = $x->copy(); $product->bfac(); }

    });

    [download]

    I get run times like these: 

          s/iter  2**14  2**13  2**12  2**11  2**10
2**14    139     --   -78%   -97%   -99%  -100%
2**13   31.3   345%     --   -88%   -97%   -99%
2**12   3.88  3488%   706%     --   -78%   -95%
2**11  0.870 15902%  3493%   346%     --   -76%
2**10  0.210 66195% 14786%  1748%   314%     --

    [download]

    With that kind of progression, 2**128 is, um, likely to take a while. :)


    --
    "Language shapes the way we think, and determines what we can think about."
    -- B. L. Whorf
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[d/l]
[select]
Re^2: undefined value as an ARRAY
by toolic (Bishop) on Aug 12, 2010 at 02:46 UTC
    When you ran your script, did it crash right away, or did it run for a long time before crashing?
    Another data point: I get the error immediately. When I try smaller numbers, I do not get the error, but it does seem to take a while. 
    This is perl, v5.8.8 built for MSWin32-x86-multi-thread

    [download]
[reply]
[d/l]
      If your script works for smaller numbers then it's probably a bug in either Math::BigFloat itself or in a library it uses .

      If it is an option for you try it on another system or with a newer version of Perl.

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