ok so for the forall we can write costume way to combine the results.
Take for example a matrix multiplication
1)
for i in arow do
for j in bcol do
for k in acol do
c(i,j) += a(i,k)*b(k,j);
and
2)
forall i in arow do
forall j in bcol do
forall k in acol do
c(i,j) += a(i,k)*b(k,j);
What I believe is ..
1st is a serial code( no big deal)
2nd is a parallel code .. it creates i*j*k number of thread internally,
each thread does the arithmetic( and return, I say it returns because my
program terminates without threads being hanged), isn't here reduction
required. When I run the parallel code ( with forall ) it takes same time.
There is no much difference.
from next time I will be sending to [email protected]. (
let me know If not)
On Mon, Mar 17, 2014 at 9:01 AM, Brad Chamberlain <[email protected]> wrote:
> It looks like you accidentally sent this to the mailing list owner alias
> rather than the mailing list itself (?).
>
> The short answer is that a reduce uses a forall loop, but collapses the
> result down to a singleton whereas the forall has no reduction step. But
> the parallelism induced by either to sweep over the values in question
> should be the same. The reduction part of the reduction step is known to
> be implemented suboptimally.
>
> -Brad
>
> ------------------------------
> *From:* Bibek Ghimire [[email protected]]
> *Sent:* Monday, March 17, 2014 6:59 AM
> *To:* [email protected]
> *Subject:* diference between forall and reduce in chapel
>
> Hey all,
> Can anyone tell me the difference that is there between reduce
> and forall in chapel. My theory is they are both the same.
>
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