[scilab-Users] Inexplicable result with scilab 5.0.2 and matrix multiplication

[François Vogel]

Looks like this one:

http://bugzilla.scilab.org/show_bug.cgi?id=2647

Francois


Sylvestre Ledru said on 13/10/2008 23:40:
> Hello,
> 
> It is most probably a bug in the printing functions... I can reproduce
> it with the binary (ie not compiled on my computer) but I can't on my
> dev version (compiled with gfortran 4.3.1)
> Once, we had a simular bug caused by a bug in gfortran. Maybe it is a
> regression.
> 
> Thanks for pointing this out.
> Sylvestre
> 
> Le lundi 13 octobre 2008 à 23:32 +0200, Christoph Dittmann a écrit :
>> Hi,
>>
>> I've got a problem with scilab 5.0.2. It seems to print certain values 
>> wrong. The following example shows the problem:
>> -->M = [1,2;3,2]; C = M^(-1)*M
>>   C  =
>>
>>      2.           1.110D-16
>>      1.110D-16    2.
>>
>> This is what I get with scilab 5.0.2 on Ubuntu 8.04 (x86) using the 
>> precompiled version from http://www.scilab.org/download/ . My problem 
>> are the 2's on the diagonal since I've no idea where they come from.
>>
>> With scilab 4.1.2, the one from the Ubuntu 8.04 repository, I get what I 
>> expect:
>> -->M = [1,2;3,2]; C = M^(-1)*M
>>   C  =
>>
>>      1.           1.110D-16
>>      5.551D-17    1.
>>
>>
>> Some further calculations with scilab 5.0.2 show that the problem seems 
>> to lie in the printing of the result and not its actual numerical value:
>> -->x = C(1,1)
>>   x  =
>>
>>      2.
>> -->x * 2
>>   ans =
>>
>>     2.
>> -->x + 0.01
>>   ans  =
>>
>>      1.01
>>
>>
>> Could that be a bug or did I just miss something crucial?
>>
>>
>> Thanks,
>> Christoph
> 
> 
>