I uploaded the latest version of Number::FormatEng (0.03) to CPAN four months ago, and all tests passed until last week. I am trying to understand why a test failed.

Only one test fails, and it happens on only one os/archname (OpenBSD.amd64-openbsd-thread-multi-ld) and on these two versions of Perl: 5.24.3 and 5.26.1. There are many passes (606) across all OS's.

The failing test is: 

#   Failed test at t/format_pref.t line 54.
#          got: '1000e-36'
#     expected: '1e-33'

[download]
This is when the test calls format_pref(1e-33). 1000e-36 is the same numeric value as 1e-33, but the point of this function is to display the number with a specific format.

I can't reproduce this because I don't have this OS or Perl version. But, from the tester report, I assume it fails on this line in FormatEng.pm: 

    my $e    = floor( log($num) / log(1000) );

[download]
where floor is from POSIX.

When the test passes, $num=1e-33, and $e is -11. When the test fails, I assume $e is -12. Perhaps log(1e-33)/log(1000) evaluates to -11.0001, or -11.1, or -11.2, etc.

Is it possible for me to fix the code to make it more portable? Or, is there a known problem with this OS for these Perl versions?

In reply to Portability of floor(log(N)) by toolic

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.