The problem also seems related to Perl version, but I can't say why. Trying the following code under various Perl versions I have access to ATM: 

c:\@Work\Perl\monks>perl -wMstrict -le
"print 'perl version: ', $];
 ;;
 $a = '-4.84800000E+001';
 $a += 0;
 $b = -48.48;
 print 'EQ' if $a == $b;
 printf qq{%0.20f ?==? %0.20f \n}, $a, $b;
"
perl version: 5.008009
-48.48000000000000400000 ?==? -48.47999999999999700000

perl version: 5.010001
EQ
-48.47999999999999700000 ?==? -48.47999999999999700000

perl version: 5.014004
EQ
-48.47999999999999700000 ?==? -48.47999999999999700000

[download]

Update: choroba has /msgd to ask if the differences in my results are due to 32- versus 64-bit build differences. As far as I can see from  perl -V (and to the best of my recollection), all the Perls I have here are 32-bit. However, the 5.8.9 I'm using is ActiveState, while the others are all Strawberries.

Update: davido /msgd to suggest different C compilers/libraries have different internal implementations for FP handling; perhaps AS Perl was compiled with Visual Studio and Strawberry with GNU/C.

Give a man a fish:  <%-{-{-{-<

In reply to Re: Converting -4.84800000E+001 to -48.48 doesn't work... but 48.49 does by AnomalousMonk
in thread Converting -4.84800000E+001 to -48.48 doesn't work... but 48.49 does by notameadow

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.