[Octave-bug-tracker] [bug #41799] Example sparse matrix created in oct-file with 0 index

[Carlo de Falco]

Follow-up Comment #6, bug #41799 (project octave):

Rik,

It is true that building the sparse matrix from 
aij format requires data duplication, nevertheless
that is THE most common way to assemble a sparse matrix,
AND it is the recommended way in most sparse linear algebra
packages including, e.g., UMFPACK, MUMPS, LIS, PETSC, etc.

While writing CSC data directly avoids this data duplication 
it is ofte EXTREMELY inconvenient when matrix elements are
accessed randomly rather than in a given order.

Most often, as for example for circuit simulators, FEM or FVM solvers etc.
matrix elements are given  with repetitions and
repeated elements are to be added. Actually in my experience this is THE most
common use of sparse matrices.

Therefore, if the first approach in the manual is not the most
recommended, it should actually be as it is the most convenient for most
applications I know of.

This said, it is true that the approach with indices in ColumnVector objects
is more similar to what is done in m-files,
yet it differs from the other two approaches shown in the same
manual page, which use 0-based indices, which I think could
be confusing ...


c.

    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?41799>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/