the temporary variable uses a value set outside of the PARFOR loop

Let' say I have the code like this:

gcp;
a=zeros(1,3);%create the zeros matric 1x3
my_cell={[1 1 1;2 2 2],[3 3 3;4 4 4],[5 5 5;6 6 6;7 7 7]}; %this is the initial cell

parfor I=1:3
    input_data=my_cell{I};%get data coordinate(x,y,z) from my_cell
    [ result ] = my_function( input_data );% The result will be generated from function named "my_function". The result is kx3 matric
    [a,~,~] = union(a,result,'rows');% add the result to the initial matrix a
end

In my code informed this warning: the temporary variable "a" uses a value set outside of the parfor loop. How can I fix this error for "parfor"

Thanks.

Answer 1

[Walter Roberson]

You cannot do that. You are trying to use|a| as a reduction variable, but union() is not one of the supported reduction operations. You will need to do something like

my_cell={[1 1 1;2 2 2],[3 3 3;4 4 4],[5 5 5;6 6 6;7 7 7]}; %this is the initial cell

N = size(my_cell,2);
a = cell(N,1);
parfor I = 1 : N
  input_data=my_cell{I};%get data coordinate(x,y,z) from my_cell
  [ result ] = my_function( input_data );% The result will be generated from function named "my_function". The result is kx3 matric
  a{I} = result;
end

a = unique(vertcat(a{:}), 'row');

[ha ha]

Thanks so much @ Walter Roberson