We help IT Professionals succeed at work.

We've partnered with Certified Experts, Carl Webster and Richard Faulkner, to bring you a podcast all about Citrix Workspace, moving to the cloud, and analytics & intelligence. Episode 2 coming soon!Listen Now

x

Double precision and iostream library

roberto022697
on
Medium Priority
565 Views
Last Modified: 2008-02-26
Hi,

the following problem:

I have a double precision number,
double x = -9.3456

Then I try to output it using the following commands:
cout.setf(ios::fixed,ios::floatfield);
cout.precision(16);
cout << x;

...and this is the result:

-9.3455999999999992

What I need to know is:

which is the number actualy stored in memory ?
what happens ?

Thanks for any help.

Roberto

Comment
Watch Question

The actual number stored in memory is:
-9.3455999999999992

This is the closest number to -9.3456 that can be stored
in the bits of a double.  Numbers are stored in base 2 (one's
and zeros).  Thus you can exactly store the numbers: 8,4,0.5,
0.25, etc. but a number like 0.1 cannot be exactly stored.

In computer science we accept this small error ( called floating
point error ) as a fact of life.

jordan

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts
Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

OR

Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.