For the record: With the recent debian version of Maxima on xubuntu12.04:
Maxima 5.27.0 http://maxima.sourceforge.net
using Lisp GNU Common Lisp (GCL) GCL 2.6.7 (a.k.a. GCL)
(%i1) 0.2+0.2+0.2;
(%o1) 0.6
(%i2) if (0.2+0.2+0.2 = 0.6) then "yes" else "no";
(%o2) no
(%i3) fpprintprec;
(%o3) 0
Same with
Maxima 5.27.0 http://maxima.sourceforge.net
using Lisp GNU Common Lisp (GCL) GCL 2.6.8 (a.k.a. GCL)
on Windows.
Volker van Nek
2012/5/16 Jaime Villate <villate at fe.up.pt>
> On 05/16/2012 09:05 AM, Evgeniy Maevskiy wrote:
>
>> (%i1) x:makelist(1/5^k,k,1,7);
>> (%o1) [0.2,0.04,0.008,0.0016,3.**2000000000000003E-4,6.**
>> 3999999999999997E-5,
>> 1.2799999999999999E-5]
>>
>> but Firefox-javascript (for example) returns precise values:
>>
>> 0.2
>> 0.04
>> 0.008
>> 0.0016
>> 0.00032
>>
>> (Windows XP, Maxima 5.27.0, Firefox 11.0)
>>
> In Ubuntu, Firefox 11.10 javascript does not show the results rounded.
> Consider for instance the page:
>
> <html><body>
>
> <script type="text/javascript">
>
> document.write(0.2+0.2+0.2);
>
> if (0.2+0.2+0.2 == 0.6)
>
> {
>
> document.write("<p>Yes</p>");
>
> }
>
> else
>
> {
>
> document.write("<p>No</p>");
>
> }
>
> </script></body></html>
>
>
> It gives me the result
>
> 0.6000000000000001
>
> No
>
> Languages that show you the results rounded might lead you into confusion.
> Consider for instance PHP 5 (in Ubuntu):
>
> print 0.2+0.2+0.2."\n";
> if (0.2+0.2+0.2 == 0.6) {
> print "Yes\n";
> } else {
> print "No\n";
> }
>
> The result is:
>
> 0.6
> No
>
> which will make you think that the two results contradict each other.
> Python and Maxima
> also show you the result without rounding.
>
> Python 2.7.2:
>
> 0.2+0.2+0.2
>>>>
>>> 0.6000000000000001
>
>> if (0.2+0.2+0.2) == 0.6:
>>>>
>>> ... print 'yes'
> ... else:
> ... print 'no'
> ...
> no
>
> Maxima 5.25:
>
> (%i1) 0.2+0.2+0.2;
> (%o1) .6000000000000001
> (%i2) if (0.2+0.2+0.2 = 0.6) then "yes" else "no";
> (%o2) no
>
>
> Regards,
> Jaime
>
>
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>