Re: Interpretation of result

[Sergei Steshenko]

----- Original Message -----
> From: JuanPi <address@hidden>
> To: address@hidden
> Cc: 
> Sent: Monday, September 17, 2012 9:59 PM
> Subject: Interpretation of result
> 
> Can anybody explain this to a simple mortal who did not take a
> rigorous numerical calculus class?
> 
> octave:89> 99999999999999999 - 99999999999999998
> ans = 0
> 
> (that is 17 digits) ...
> 
> Thanks!!
> 
> -- 
> JuanPi Carbajal
> -----
> "The bad economist pursues a small present good, which will be
> followed by a great evil to come, while the true economist pursues a
> great good to come, at the risk of a small present evil." - Frédéric
> Bastiat
> -----
> http://ailab.ifi.uzh.ch/carbajal/
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Do you know how floating point numbers are represented in modern computers ?

If not, I suggest to start from here: 
https://en.wikipedia.org/wiki/Floating_point .

The concepts to grasp are, first of all, mantissa, exponent, denormalization.


I want to disappoint you even more - generally speaking, in computers we have

a1 + a2 + ... + aN != aN + aN-1 + ... + a1.

Regards,
  Sergei.