Le 12/05/2015 08:34, Stéphane Mottelet a écrit :
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Le 11/05/2015 21:16, Samuel Gougeon a écrit :
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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?
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