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

[Samuel Gougeon]

Hello Stéphane,

Le 11/05/2015 15:03, Stéphane Mottelet a écrit :
> Hello Scilab devs/masters,
>
> For performance purposes, i need to implement a function which is 
> missing to Scilab, allowing to set at once all non-zero terms of a 
> sparse matrix. Some other languages have this feature, e.g. Julia 
> allows to write such things.
>
> A.nzval=v
>
> of course this is interesting when the sparsity pattern does not 
> change but actual element values do. I noticed that the use of 
> "sparse" to reconstruct matrices in this context is the main 
> bottleneck of my code... In Scilab the logical name of such a command 
> should be "spset" and used like this
>
> spset(A,v)

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)  syntax (unless nzval -- that could rather be nzpos -- is 
implicit)?

Anyway, in a more general way,  i agree that an element-wise assignment 
operator would be very welcome, as well for lists, structs and cells -- 
say heterogenous -- containers.

Whether
[A,B,C, D] = ("hello", %t, (1-%s)^2, list("bye", %pi) )
sets distributively A = "hello", B=%t, C = (1-%s)^2, D = list("bye", %pi)
yet,
L = list(); L(3) = "ok"
L(:) = ("hello", %t, (1-%s)^2)  // does not work
A pity!

Regards
Samuel