Hi,
since two days I am fighting with X10 to formulate a simple matrix vector
multiply. Apparently I am thinking in the wrong direction. Perhaps someone can
correct me here.
My essential idea is the following.
def ClassicMatrixMultiply() {
finish ateach (p in v2.dist() ) {
[... some code...]
v2(p) = ((A|d)*linev).reduce(double.+,0);
}
finish v = (v2 as Array[double](v.dist()) );
}
Here
- A is a distributed Array[double], a square matrix of size n*n,
- v an Array[double] of rank 1, (v.size == n), placed at Places.FIRST_PLACE,
- v2 an Array[double] of rank 1, distributed the same way as any column of A.
- all are var (not val or const).
In clear text the line v2(p) should read "multiply the row of A that
corresponds to p with v. To make that happen, I tried to set up a distribution
that describes the "row of A that corresponds to p". My following attempt
looks very clumsy and the X10 compiler doesn't compile it either.
(The following lines go into [... some code...] above).
val j:Int = (p.coords())(0);
val r:Region = ( ([j..j] as Region(1))
* A.region.projection(1));
val d:Dist = A.dist().intersection(r);
val linev = (v as Array[double](d));
The compiler hick-ups on the expression A.dist().intersection(r). I frankly
don't understand, why. Both, A.dist() and r are having the same rank.
Shouldn't that suffice ? Any one any explanation ?
I would expect that there is a better way to do this. So I am happy with any
suggestions.
--
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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Geschäftsführung: Martin Jetter (Vorsitzender),
Reinhard Reschke, Christoph Grandpierre,
Klaus Lintelmann, Michael Diemer, Martina Koederitz
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