[petsc-dev] [petsc-users] ublas sparse matrix bindings?

Matthew Knepley knepley at gmail.com
Mon Jul 5 09:05:38 CDT 2010

On Mon, Jul 5, 2010 at 3:50 PM, Jed Brown <jed at 59a2.org> wrote:

> On Sat, 3 Jul 2010 15:41:53 +0300, Aron Ahmadia <aja2111 at columbia.edu>
> wrote:
> > I am not sure I  understand your argument here (I apologize if I talk
> past
> > you, please feel free to clarify).  I am surmising from the rest of your
> > paragraph that you feel it would be most beneficial to users to have the
> > full flexibility of mixed-precision with matrices/vectors, i.e. A = A1 +
> A2,
> > where A1 is single-precision and A2 is double-precision.  The layer at
> which
> > you express your linear algebra algorithms should be unaware of the data
> > that composes a given matrix A.
> Consider a sparse matrix consisting of 12x12 blocks operating on vector
> blocks with 3 single precision reals, 6 double precision reals, and 3
> double precision complex.  Now write a templated factorization that
> operates on these (user-defined) blocks.  Ideally this would merely
> involve the user defining
>  struct Field {
>    float a[3];
>    double b[6];
>    complex double c[3];
>  };
>  Matrix<int64_t,Field,Field> A;
> but I don't know how to make that work.  All I can think of is an
> expression template solution operating on recursive types, which strikes
> me as terribly confusing to write and use, as well as perhaps having
> padding and ordering issues.

Can we think up an easy DSL or library solution?


> Jed

What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
-- Norbert Wiener
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