The following code:
class D {
public static def main(args:Rail[String]!){
R: Region = 1..4;
D: Dist = Dist.makeCyclic(R);
val data_squares = Array.make[Int](D, ((i):Point) => i*i);
for (p in D) {
Console.OUT.println( "Array index: " + p + " distributed place :" +
D(p));
// this is the problem part, but this is how I understood arrays
Console.OUT.println( "Array element: " + (at (D(p)) data_squares(p)));
// how can I access e.g. data_squares(3) and its value and place.
// using 2.0 java back end on eclipse
}
}
}
produces the following output:
Array index: (1) distributed place :(Place 0)
Array element: 1
Array index: (2) distributed place :(Place 1)
Array element: 4
Array index: (3) distributed place :(Place 2)
Array element: 9
Array index: (4) distributed place :(Place 3)
Array element: 16
There are two changes from the code below.
First, the iterator for the for loop is changed to "for (p in D)...".
Note that the type of p is not specified explicitly. This permits the
compiler to infer the type of p as Point(D.rank) -- this is necessary so
that the subsequent array access data_squares(p) can work --
data_squares must be accessed with a point of the right rank (D.rank).
Alternatively you could also write "for (p: Point(D.rank) in D)...".
(We are working on some changes to type checking in X10 so that this
first change would not be needed.)
Now the second change is that X10 requires that the remote locations be
accessed within an "at"statement or expression so that by just looking
at the code you can see where there may be a possible inter-place
communication. Hence the access data_squares(p) should be wrapped in an
at statement which specifies the place where that data item is located,
hence "(at (D(p)) data_squares(p))".
Hope this helps,
Best,
Vijay
Haris H wrote:
> Hi guys,
> can somebody clear this up for me please.
> I can not get my head around this element manipulation in distributed arrays
> in 2.0.
>
> Here is the overly simplified code but represents my problem,
> so please tell me what am I doing wrong and what it should be.
>
> I am having trouble understanding accessing elements of the array and their
> distributed location.
>
> Thank you.
>
> public static def main(args:Rail[String]!){
>
> R: Region = 1..4;
> D: Dist = Dist.makeCyclic(R);
>
> val data_squares = Array.make[Int](D, ((i):Point) => i*i);
>
> for (val p: Point in D) {
> Console.OUT.println( "Array index: " + p + " distributed place :" +
> D(p));
>
> // this is the problem part, but this is how I understood arrays
>
> Console.OUT.println( "Array element: " + data_squares(p));
>
> // how can I access e.g. data_squares(3) and its value and place.
> // using 2.0 java back end on eclipse
> }
> }
> ------------------------------------------------------------------------------
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> proactively, and fine-tune applications for parallel performance.
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>
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>
>
------------------------------------------------------------------------------
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