On Fri, Jan 31, 2020 at 4:19 AM Jeremy Theler wrote:
>
> On Thu, 2020-01-30 at 18:05 -0500, Matthew Knepley wrote:
> > On Thu, Jan 30, 2020 at 6:04 PM Jeremy Theler
> > wrote:
> > > On Thu, 2020-01-30 at 21:10 +, Smith, Barry F. wrote:
> > >
> > > > MatGetSubMatrix() and then do the
On Thu, 2020-01-30 at 18:05 -0500, Matthew Knepley wrote:
> On Thu, Jan 30, 2020 at 6:04 PM Jeremy Theler
> wrote:
> > On Thu, 2020-01-30 at 21:10 +, Smith, Barry F. wrote:
> >
> > > MatGetSubMatrix() and then do the product on the sub matrix
> > then
> > > VecSum
> > >
> >
> > Ok, I
On Thu, Jan 30, 2020 at 6:04 PM Jeremy Theler wrote:
>
> On Thu, 2020-01-30 at 21:10 +, Smith, Barry F. wrote:
>
> > MatGetSubMatrix() and then do the product on the sub matrix then
> > VecSum
> >
>
> Ok, I have it working in a single-processor and throws the expected
> value. Yet I have a
On Thu, 2020-01-30 at 21:10 +, Smith, Barry F. wrote:
> MatGetSubMatrix() and then do the product on the sub matrix then
> VecSum
>
Ok, I have it working in a single-processor and throws the expected
value. Yet I have a segfault in parallel when I ask for the IS
corresponding to the
"Smith, Barry F. via petsc-users" writes:
> MatGetSubMatrix() and then do the product on the sub matrix then VecSum
If you're only doing it once or the relevant rows are changing, it may
be cheaper to multiply the whole matrix by a vector instead of creating
a submatrix. If you have many of
MatGetSubMatrix() and then do the product on the sub matrix then VecSum
Barry
> On Jan 30, 2020, at 3:02 PM, Jeremy Theler wrote:
>
> Sorry if this is basic, but I cannot figure out how to do it in
> parallel and I'd rather not say how I do it in single-processor mode
> because I would
Sorry if this is basic, but I cannot figure out how to do it in
parallel and I'd rather not say how I do it in single-processor mode
because I would be ashamed.
Say I have a matrix and I want to multiply a row times a vector to
obtain a scalar. Actually I would like to choose some rows, multiply
