OT: Re: is dwt alive?

aarti_pl aarti at interia.pl
Sun Jul 11 14:39:23 PDT 2010

W dniu 2010-07-11 22:45, "Jérôme M. Berger" pisze:
> aarti_pl wrote:
>> I just would like to say that it is a great news! After discovering that
>> for Java:
>> ----
>> double sum = 0.0;
>> for (int i = 0; i<  10; i++) sum += 0.1;
>> ----
>> sum is equal: 0.9999999999999999
>> I am looking at D with greater and greater sentiment :-) SWT and good
>> precision of calculations is necessary for my program...
> 	Are you sure D is better? In C, you get 0.99999999999999988898 (not
> surprising since 0.1 cannot be represented exactly in base 2) and I
> would expect D to give the same result...
> 		Jerome

On my computer it is exactly 1.0 (one).

I know that there is explanation of why it is like that, as I found 
article about it. I did not get deeper into it (good few pages of text) 
as I believe there must better solution for programmers.

My calculator shows proper results, spreadsheet shows proper results and 
I think that calculations in my program for such a big fractions should 
also give correct result.

Just thought: maybe calculations in D are done internally in more than 
64bits and then casted into 64bits? It's a bit surprising for me that C 
is also wrong about this sum...

Marcin Kuszczak

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