The specified variable appears inside a parfor loop within different indexing expressions. Because the indices are inconsistent across the uses of the array created by the parfor loop, MATLAB sends the entire array to each worker, resulting in high data communication overhead. For example, the following code elicits this message for c, because there are two different indexing expressions for it:

 c = foo();
 parfor i = 1:N
     a(i) = c(i,1);
     b(i) = c(i,2);
 end


When the indices are the same for all instances of the indexed variable, the variable is classified as sliced, and MATLAB sends only the required elements to the workers for each iteration of the parfor loop.

In some cases, there is no way to avoid this message, and therefore you should suppress it, as described in Adjust Code Analyzer Message Indicators and Messages

However, in most cases, you can use additional variables to avoid this problem. For example, in the following code, x and y are sliced and do not elicit the message. In effect, the temporary variables make it clear to MATLAB which data to ship to the workers:

     c = foo();
     x = c(:,1);
     y = c(:,2);
     parfor i = 1:N
         a(i) = x(i);
         b(i) = y(i);
     end


For more information, see Classification of Variables in parfor-Loops.