[Scilab-users] Is cond([]) 0 or 1 ? (bug 15579)

[Samuel Gougeon]

Le 27/05/2018 à 23:23, philippe a écrit :
> Le 27/05/2018 à 19:51, Samuel Gougeon a écrit :
>> [...]
>>
>> Please let us know more about your proposal for 1 instead of 0.
> I can't say it now, the best value also depends on the compatibility of
> this value with others assigned to matrix functions with argument [].
> I would like to check it before, but with the example you mention 0 looks
> a better choice.

As far as i understand, rcond(X) should return the inverse of cond(X,1).

In Scilab, rcond([]) returns []. This looks pretty inconsistent with any 
Scilab cond([],p) result,
and does not help much for this longly empty cond([]) discussion.

In Octave, rcond([]) returns %inf, that's consistent with cond([])==0.

However, still, a guy whose det() is 1 and norm() is 0 is really a 
special guy.

If we have no evidence/reference on the fact norm([]) is 1 rather than 0,
i guess that we will change Scilab's cond([]) to 0.
May the Scilab creator having initially set 1 read us and correct us if 
it's needed.

Cheers
Samuel