Re: Exact zero

[Martin Helm]

Am Freitag, 27. Mai 2011, 20:58:20 schrieb Martin Helm:
> Am Freitag, 27. Mai 2011, 20:43:38 schrieb Patrick Carle:
> > This prints a list of numbers, one of which is exactly zero :
> > 
> > fprintf('%.1e\n',((3:14)-14/2)*.01);
> > 
> > But when the 3 is changed to a 2 in ie:
> > 
> > fprintf('%.1e\n',((2:14)-14/2)*.01);
> > 
> > The number that used to be exactly zero is now -1.7e-018. Is this a bug?
> > Is there a way to force this to be exactly zero?
> > 
> > Thanks!
> 
> 0.01 can not be represented in IEEE 754 floating point, this leads to
> rounding errors. And no - it is not a bug.
> 
> A simple introduction is this
> http://en.wikipedia.org/wiki/Floating_point
> (Representable numbers, conversion and rounding)


Ah sorry, I looked more in detail into it, are you sure?
I cannot see that with 3.4 and it should not happen with this statement since 
(2:14)-14/2) is a sequence of exact integer values afterwards multiplied by 
0.01.

Which version are you using and on which operating system?