Dynamically Creating Variable Alternatives

Hi,

Currently I have a 3D matrix of zeros (1000,1000,430) and I need to iterate through slices 1:430. I want each slice done in parallel as each slice can be done independently and I have access to a super computer with many cores and each slice takes around 4800 seconds on my PC. Each slice of zeros will then be given different values in each index defining locations of the brain. Without parfor I can just simply call my 3D preallocated matrix of zeros and redefine different indexes. However, this matrix can't be called and edited by different cores in parallel. This means I need an independent matrix for each slice. Currently, I have preallocated matrixes A1-A430 using the forbidden eval function in a for loop. However, I am unsure how to call these matrixes in a for loop without using the eval function. For example when I am in slice 100 I would need to edit A100. I am unsure how to do this without using eval. On that note I assumed other structures cannot be called in parallel and this is why I stuck with the forbidden dynamic variable creation. Any advice would be greatly appreciated.

[Stephen23]

https://www.mathworks.com/help/parallel-computing/transparency.html

[Eric Hoffmann]

Wow such a useful link. I am confused how I never came across this in my own research. Hiding eval in a function would fix the problem I believe. I will accept the other answer as that has also worked and doesn't require dynamic variables, but this will be the route I will go down if that doesn't work in the end.

Answer 1

[Walter Roberson]

 parfor sliceno=1:size(Data, 3)
   slice = Data(:, :, sliceno);
   change slice
   Data(:, :, sliceno) = slice;
  end

[Eric Hoffmann]

Wow thank you for such a quick response. I was indexing with sliced variables in the wrong manner as you correctly show above. How dumb of me! I also wanted to include the link below as that fixes the next problem that appears once applying the correction above. Thanks again everyone!

https://www.mathworks.com/matlabcentral/answers/817330-how-to-resolve-indexing-the-sliced-variable-error-in-the-case-of-for-nested-with-parfor