>> I understood that assignment of arrays is by value, like
>> ArrayA = ArrayB
>> makes A an independent copy of the array B taken that their domains
>> match, right?
>
> Mostly right, though their domains need not match. See "20.5 Array
> Assignment" in the language spec:
>
> http://chapel.cray.com/spec/spec-0.96.pdf
>
> or [test/release/]examples/primers/arrays.chpl for a primer-based
> introduction.
>> If I wanted A to reference to the B how should I write in
>> that case?
>
> At present, see "20.9 Array Aliases" in the language spec. This can also
> be done in a constructor context, as some examples within the
> BlockDist.chpl code demonstrate (search on "=>").
>
> Longer-term, we'd like to support this as:
>
> ref A = B;
>
> but it doesn't work as generally as we'd ultimately like.
>> Also, what is the effect of writing
>> DomainA = DomainB
>
> See Section "19.8.1 Domain Assignment" in the language spec as well as the
> cross-reference to "20.11 Association of Arrays to Domains" (or, again,
> the arrays.chpl primer example).
Thanks, I had missed those parts in the language spec...
>> Would you expand a bit on this? Namely, where should I stop the timer,
>
> It all depends on what you want to time. Given a loop of the form:
>
> coforall loc in MyLocs {
> on loc do {
> ... do some work on that locale ...
> }
> }
>
> I'd imagine you'd probably want to do this:
>
> coforall loc in MyLocs {
> on loc do {
> // start timer
> ... do some work on that locale ...
> // stop timer
> }
> }
>
> to time the work done by each locale. See "32.2.7 Time" in the language
> spec for information on the timing routines we provide, or
> [test/release/]examples/primers/timers.chpl in the source tree for a
> code-based primer.
>> and how should I return the gathered information to the user?
>
> I don't have any particular vision here. The forall loops don't have any
> interface for returning timings to the callsite, so you'd presumably need
> to tuck this information away into your classes and then support a query
> into the classes to retrieve it (or else print it out to the console).
>
> Today, to call a method on one of the classes implementing your
> domain/array value, you'd use:
>
> myDom._value.mySpecialDomainMethod()
>
> or:
>
> myArr._value.mySpecialArrayMethod()
>> Also I'd like to be able to turn the timings on/off during runtime, how
>> should I pass this argument?
>
> You could either make a config const that would control it for all
> instantitations of your domain map, or make it an argument to the domain
> map itself and set it on a per domain map basis. We don't support
> optional constructor arguments to domains/arrays at present outside of the
> domain map, though you could use the same ._value-based backdoor in the
> previous paragraph to set/reset a value dynamically if you wanted.
Just to make sure: the language spec says that iterator and loop body are
executed in interleaved manner, so does that mean the these() method (leader
iterator) in BlockDom returns only after the loop bodies are actually executed?
Ie. timing body of coforall loop in these() will measure how long forall loop
takes to execute on each locale.
In one of the previous post Brad described a cut distribution that existed in
ZPL. Do you know of any papers about that, or papers about any other efficient
ways of writing efficient, variable sized distributions? My implementation
isn't quite as efficient as I'd like, though I'll see what kind of improvement
some caching will bring...
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