dlarray and parfor gives error

Hello together,

I want to accelerate my compuations with parfor while using dlarray.

My compuation looks like this:

parfor i = 1:num_features
    feature = ... some calculations ...   
    loss_temp(i) = mse(feature,feature_ground_truth,'DataFormat','CB')
end

loss = sum(loss_temp);
  
gradients = dlgradient(loss,dlnet.Learnables); 

It gives me the error:

Error using dlarray/dlgradient

Value to differentiate is not traced. It must be a traced real dlarray scalar. Use dlgradient inside a function called by dlfeval to trace the variables.

Error in modelGradients (line 67)

gradients = dlgradient(loss,dlnet.Learnables);

Does this mean, dlarray information is lost during parfor calculation and it is not compatible with it?

Thanks for your help.

Edit:

There is a website Link. Do I have to use dlaccelerate somehow? Thanks.

Answer 1

[Roman Foell]

Thanks all,

I already got the answer:

Calculate the gradients inside the parfor loop and combine it outside.

Possible, because the gradient of a sum is the sum of the gradient summands.

Thanks.