PARFOR slicing of user-defined objects

I have a user-defined class with its own overloaded subsref and subsasgn methods to define indexing expressions like A(:,:,i). My question is, how would parfor treat a loop like the following with respect to slicing,

parfor i=1:N
    
    x(:,i)=some_function( A(:,:,i) );
    
end

Will my object A be sliced as a normal numeric array would, and if so how is my overloaded subsref/subsasgn method involved in this process? Will parfor execute my subsref method when it tries to extract a chunk A(:,:,m:n) to send to the workers?

Answer 1

[Edric Ellis]

The parfor machinery decides whether a variable reference is "sliced" or not by examining the form of indexing used, paying no regard to the type of the variable. So, in your example, A will indeed be sliced. Your indexing overloads will be called on the client as part of the slicing operation, and also on the workers. The parfor machinery will send contiguous blocks of A of size MxNxp to the workers in groups known as "intervals" (with an interval size p), and then on the workers, these blocks will be further indexed to create the MxNx1 slices.

[Matt J]

Very good! Thanks.