From the perlform manpage: 
       Picture fields that begin with ^ rather than @ are treated
       specially.  With a # field, the field is blanked out if
       the value is undefined.  For other field types, the caret
       enables a kind of fill mode.

[download]
So change your @#### to ^####, and make sure the values you want to suppress are undefined.

The second problem is that using an undefined value when warnings are enabled will generate several warning messages. I suggest disabling warnings within the format, like this: 

{ no warnings;
format STDOUT =
@<<<<<<<<<<<<<   ^####   @#####.##
$output[$i], $output[$i+1], $output[$i+2]/1024
.
}

[download]

In reply to Re: Supressing zero values in formatted reports by robin
in thread Supressing zero values in formatted reports by ryan

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.