Re: Re: ParrallelDo and set::noval

• To: mathgroup at smc.vnet.net
• Subject: [mg102704] Re: [mg102697] Re: ParrallelDo and set::noval
• From: Patrick Scheibe <pscheibe at trm.uni-leipzig.de>
• Date: Thu, 20 Aug 2009 04:55:30 -0400 (EDT)
• References: <h63cgg\$1b6\$1@smc.vnet.net> <h6duf8\$h1c\$1@smc.vnet.net>

```Hi,

why do you create the table in the first place? Just let ParallelTable

grid = Range[4, 50, 0.5];
DistributeDefinitions[grid];
testArray1 = ParallelTable[
{i, If[4 <= grid[[i]] <= 50, 1, 0]}, {i, 1, Length[grid]}]

but if you insist to know what was wrong with your code, please have a
look at SetSharedVariable[...]

grid = Range[4, 50, 0.5];
testArray = Array[Null, {Length[grid]}];
DistributeDefinitions[grid];
SetSharedVariable[testArray];
ParallelDo[iroot = 0;
rr = grid[[i]];
Which[4 <= rr <= 50, iroot = 1];
testArray[[i]] = {i, iroot};, {i, 1, Length[grid]}]

testArray===testArray1

Out[12]= True

Cheers
Patrick

On Wed, 2009-08-19 at 07:02 -0400, guerom00 wrote:
> As requested, a minimal example which illustrate the problem.
>
> The following sequential code works fine :
>
> grid = Range[4, 50, 0.5];
> testArray = Array[Null, {Length[grid]}];
>
> Do[
>  iroot = 0;
>  rr = grid[[i]];
>  Which[
>   4 <= rr <= 50, iroot = 1
>   ];
>  testArray[[i]] = {i, iroot};
>  , {i, 1, Length[grid]}]
>
>
> The equivalent parallel code :
>
> grid = Range[4, 50, 0.5];
> testArray = Array[Null, {Length[grid]}];
>
> DistributeDefinitions[grid,testArray];
>
> ParallelDo[
>  iroot = 0;
>  rr = grid[[i]];
>  Which[
>   4 <= rr <= 50, iroot = 1
>   ];
>  testArray[[i]] = {i, iroot};
>  , {i, 1, Length[grid]}]
>
> returns "Set::noval: Symbol testArray in part assignment does not have
> an immediate value." Somehow the DistributeDefinitions[] is not
> sufficient to indicate to each kernel that I have initialized the list
> testArray.
>
> Thanks in advance for any help :)
>

```

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