Le 12/05/2015 10:30, Samuel Gougeon a écrit :
Le 12/05/2015 10:14, Samuel Gougeon a écrit :
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.
exactly !

There could be a convention: when v(i) is %nan, the existing value could be unchanged and v(i) ignored. When v(i)==0, then A's length is automatically changed. This can make forthcoming assignments very hazardous.

Samuel

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Département de Génie Informatique
EA 4297 Transformations Intégrées de la Matière Renouvelable
Université de Technologie de Compiègne -  CS 60319
60203 Compiègne cedex

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