[Scilab-users] slash (/) help page confusing ?

[Stéphane Mottelet]

Le 30/08/2018 à 10:03, philippe a écrit :
> Le 30/08/2018 à 09:42, Stéphane Mottelet a écrit :
>> Le 30/08/2018 à 09:32, philippe a écrit :
>>>   
>>> [...]
>>> but in the help page it is written that "X=A/B is the solution of X*B=A"
>>
>> For square A, B, invertible B, "A/B" means "A*inv(B)", hence
>> B*(A/B)=B*A*inv(B) cannot be equal to A (matrix product is not commutative)
> I know this but for non-square matrices scilab use the opposite
> convention,
OK. To me, the / operator does not correctly check the compatibility of 
respective dimensions of A and B. The statements:

A=1;
B=[1 2 3];
X=A/B

should raise an error because A and B must have the same number of 
columns if the equality X*B=A has to make sense.

With the following statements

A=1;
B=[1 2 3]';
X=A/B
X*B

we get a coherent result:

--> X=A/B
  X  =

    0.   0.   0.3333333

--> X*B
  ans  =

    1.

S.
> IMHO it's confusing, and the case of a scalar in the help
> page doesn't mention this change. the help page should be updated.
>
> Best regards,
>
> Philippe
>
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-- 
Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet