[Scilab-users] spec can crash scilab

[Antoine Monmayrant]

Hello all,

I might have found a workaround, but I still need to ensure that I get 
exactly the same end results in my code.
It seems that I can replace:

[W2, gammas] = spec(A); //crashes

by

[al,be,W2]=spec(A,eye(A)); //fine
gammas=diag(al./be);

If anyone has a solution with eigs, I'll take it.
Could my workaround help investigate where the bug is in the gateway 
between scilab and lapack?

Cheers,

Antoine

On 05/05/2021 08:22, Antoine Monmayrant wrote:
>
>
> On 05/05/2021 00:09, Samuel Gougeon wrote:
>> Le 04/05/2021 à 16:38, Antoine Monmayrant a écrit :
>>>
>>> Yes, it does the same
>>>
>>> So this bug is still a problem, at least on Ubuntu.
>>> Can you guys try to run spec.tst on his machine and comment on 
>>> https://bugzilla.scilab.org/show_bug.cgi?id=15330 ?
>>>
>>
> Hello Samuel,
>>
>> Besides, how confusing and messy the notations on the spec () 
>> documentation page are! ...
>>
>>   * R defined twice but differently among arguments
>>   * L defined among arguments but not used in syntaxes
>>   * Q and Z used in syntaxes but not described among arguments
>>   * al, be used in descriptions, instead of alpha and beta listed in
>>     arguments
>>   * E used in the description, but not in arguments nor in syntaxes...
>>
>> and so on..
>> In addition, notations differ from a language version to another one...
>> Some clarification is urgently required.
> Indeed.
> It is also a big problem for portability to get such a basic 
> functionality (solving eigenvalue problems in a linear algebra 
> software!) only working on some platforms!
>>
>> In next release, eigs() -- mainly based on the former Arnoldi module, 
>> that becomes internal -- is listed in the same help section. Have you 
>> tried it?
> Well, I might be a bit far from my field of expertise, but it does not 
> seem that eigs can compute all the eigenvalues/eigenvectors, does it?
> It seems that by default it computes the 6 biggest ones and can go up 
> to rank(A)-2.
>
> In my use case, I need all the eigenvalues...
>
> Antoine
>
>>
>> Samuel
>>
>>
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