Yes, that is the problem. 

   DB<27> x $start
 0  0.6
   DB<28> x $store->[3]
 0  0.6
   DB<29> x 0.6 == $start
 0  ''

[download]
jeroenes, repeat the above and do "x $start-0.6" and you may be enlightened.

Update: So we all can take part in the fun: 

  DB<1> $x=0.6
  DB<2> x ($l,$h)=unpack"L*",pack"d",$x
0  858993459
1  1071854387
  DB<3> x $y=unpack"d",pack"L*",$l+1,$h
0  0.6
  DB<4> x $z=unpack"d",pack"L*",$l-1,$h
0  0.6
  DB<5> x $y-$x
0  '1.11022302462516e-016'
  DB<6> x $x-$z
0  '1.11022302462516e-016'
  DB<7> x $y-$z
0  '2.22044604925031e-016'
  DB<8> x unpack"d",pack"L*",$l-4,$h
0  0.6
  DB<9> x unpack"d",pack"L*",$l-5,$h
0  0.599999999999999
  DB<10> x unpack"d",pack"L*",$l+4,$h
0  0.6
  DB<11> x unpack"d",pack"L*",$l+5,$h
0  0.600000000000001

[download]
Welcome to floating point.

        - tye (but my friends call me "Tye")

In reply to (tye)Re: Comparison misses a true in *some* cases by tye
in thread Comparison misses a true in *some* cases by jeroenes

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.