[Scilab-Dev] Question about sparse(ij,v,mn) internals

[Samuel Gougeon]

Le 12/05/2015 08:34, Stéphane Mottelet a écrit :
> .../...
>
> Le 11/05/2015 21:16, Samuel Gougeon a écrit :
>> .../...
>> I may miss something: how do you specify the position of terms to be 
>> set with the v content? Is A already set, and you just want to 
>> replace its nz terms? Is .nzval the "list" of positions (in such a 
>> way that we could read A(nzval) .= v , and then what is the 
>> equivalent with the spset(A,v)
> no, nzval is really the field name such that A.nzval has the value v 
> sucht that [ij,v]=spget(A). In Julia, the fields of a sparse matrix are
>
> julia> A.
> colptr m       n       nzval   rowval
>
> colptr and rowval give the indices for the classical column compressed 
> format. The nzval field is of read-write type so that the non zero 
> elements can be updated by "A.nzval=v" if v has the correct size and 
> corresponds to correctly ordered (column-wise) unique (i(k),j(k),v(k)) 
> pairs.

OK. So, unless i misunderstand you, this syntax is used only to update 
values at their current positions, not to set new positions or modify ones.
I guess that if v is too long, its extra values are ignored, and if it 
is too short, only the available values are reset. Aren't they? Or an 
error message is then emitted?