On Sunday 17 January 2010 12:21:04 pm Josh Milthorpe wrote:
> Hi Christoph,
>
> I won't comment on whether there are better ways to implement a
> matrix-vector multiply.
>
> The immediate problem here is that the Region.product(...) operation
> doesn't combine the rank constraints of the two operands. In other
> words, it is currently defined as:
>
> abstract public global def product(that: Region): Region;
>
> whereas it should be:
>
> abstract public global def product(that: Region):
> Region(this.rank+that.rank);
>
> Unfortunately such arithmetic constraints will not be possible until X10
> 2.1, so for the time being, the rank constraint must be lost.
>
> For now, you could perform a cast to restore the lost rank constraint:
>
> val r = ( ([j..j] as Region(1)) * A.region.projection(1)) as Region(2);
>
> Once X10 2.1 is released, such a cast should no longer be required.
>
> I would also suggest that you drop the explicit type declarations for
> values, as discussed in Bard's earlier posting:
> http://sourceforge.net/mailarchive/message.php?msg_name=OF1917566B.E32908BD
> -ON852576A6.0007CA46-852576A6.000916B7%40us.ibm.com
>
> For example just write
> val r = ...
> instead of
> val r:Region =
>
> This will ensure that type information (including the rank constraint)
> is preserved as far as possible.
>
> Kind regards,
>
> Josh
>
Josh,
that you for your suggestions. I was trying them today and the code looks now
as follows.
/**
* Method to multiply matrix A with vector v
*/
def ClassicMatrixMultiply() {
finish ateach (p in v2.dist() ) {
val j = (p.coords())(0);
val r = ( ([j..j] as Region(1))
* A.region.projection(1)) as Region(2);
val d = A.dist().intersection(r);
val linev = (v as Array[double](d));
v2(p) = ((A|d)*linev).reduce(double.+,0);
}
finish v = (v2 as Array[double](v.dist()) );
}
But still the X10 compiler complains about
val d = A.dist().intersection(r);
with the following message.
Multiple messages: Method intersection(x10.lang.Region
{_self10885689.rank==x10.lang.Dist#this.region.rank}) in x10.lang.Dist
{_self10925187==matmul#this.A.dist} cannot be called with arguments
(x10.lang.Region
{_self10868754==r, r.rank==2}); Call invalid; actual parameter of type |
x10.lang.Region
{_self10868754==r, r.rank==2}| cannot be assigned to formal parameter type |
x10.lang.Region
{r.rank==matmul#this.A.dist.region.rank}|. Method
intersection(x10.lang.Region
{_self10885689.rank==x10.lang.Dist#this.region.rank}) in x10.lang.Dist
{_self10883810==matmul#this.A.dist} cannot be called with arguments
(x10.lang.Region
{_self10868754==r, r.rank==2}); Call invalid; actual parameter of type |
x10.lang.Region
{_self10868754==r, r.rank==2}| cannot be assigned to formal parameter type |
x10.lang.Region
{r.rank==matmul#this.A.dist.region.rank}|.
I have difficulty understanding this error message. It seems to tell me that
the
construct A.dist().intersection(r) is illegal, but it doesn't tell me why.
Do I miss something here ?
--
Mit freundlichen Grüßen / Kind regards
Dr. Christoph Pospiech
High Performance & Parallel Computing
Phone: +49-351 86269826
Mobile: +49-171-765 5871
E-Mail: christoph.pospi...@de.ibm.com
-------------------------------------
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