[Scilab-users] sparse in Scilab 6.0.0

[Stéphane Mottelet]

Please read the Matlab's help page for sparse at 
https://fr.mathworks.com/help/matlab/ref/sparse.html :

S = sparse(i,j,v) generates a sparse matrix S from the triplets i, j, 
and v such that S(i(k),j(k)) = v(k). The max(i)-by-max(j) output matrix 
has space allotted for length(v) nonzero elements._*sparse adds together 
elements in v that have duplicate subscripts in i and j.*__*
*_
Scilab devs have always wanted to have no strings attached to Matlab 
conventions. Sometimes this has been a good idea, but here this is 
definitely not the case...

S.

Le 08/07/2017 à 19:09, Samuel Gougeon a écrit :
> Hi,
>
> Le 08/07/2017 à 10:00, Pinçon Bruno a écrit :
>> Le 08/07/2017 à 04:13, Taiji HAGIWARA a écrit :
>>> Dear all,
>>>
>>> I have a question on "sparse" function in ver.6.0.0
>>> Sparse function in ver.6.0.0 returns different answer compared to 
>>> ver.5.2.2.  I am using Scilab 6.0.0 on Windows 10 (64bit)
>>>
>>> When we set same (i,j) factor twice or more,
>>> ie.
>>> ij=[i1,j1;
>>>     i1,j1]
>>> v=[a1;
>>>     a2]
>>>
>>> Scilab 5.5.2 used to return the sum of corresponding value, a1+a2.
>>> But Scilab 6.0.0 now returns the last entry, a2.
>>>
>>> Is it a bug?
>>> Otherwise, is it a intended revision?
>>
>>       Hi all,
>>
>>     If it is the case, it's for sure a very bad idea : the sum feature
>>    of the sparse function is used to build finite element matrices 
>> fastly
>>    in those softwares (matlab like). At least the usual behavior 
>> could be
>>   changed by an additionnal option parameter (with the default set to
>>   get the old behavior).
>
> From a general non-sparse and non-finite-element point of view, this 
> feature looks like a hack.
> Now, it has never been documented in Scilab. Then, it was considered 
> and reported as a bug
> @ http://bugzilla.scilab.org/7675
> If apparently it needs to be restored, it clearly needs to be 
> documented, and actually asks
> for an option. Could you -- Bruno and Stephane -- comment the report 
> please?
>
> Thanks.
> Samuel
>
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