Beefy Boxes and Bandwidth Generously Provided by pair Networks
"be consistent"
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??
If you care about your money, use Math::BigFloat, as dragonchild suggested.

As others have said, the problem is that floating point binary can't represent most decimal fractions exactly. It's analogous to the way that 1/3 is a repeating decimal (0.3333...). 0.95 and 0.9 are both repeating binary numbers. As can you see, it goes both ways: even 1/3 in trinary notation does not repeat: 0.1.

The solution is to use "fixed point" or "arbitrary precision" decimal arithmetic. This is usally implemented internally as an integer (or byte array) with a scale. I'm not sure how Math::BigFloat does its job, but it is the standard module for arbitrary precision arithmetic in Perl.


In reply to Re: 4253.95 + 0.9 = 4254.84999999999 (need help to interpret internals) by mdillon
in thread 4253.95 + 0.9 = 4254.84999999999 (need help to interpret internals) by jplindstrom

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



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others romping around the Monastery: (4)
As of 2024-03-28 22:28 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found