Skipping iteration on child throwing a warning
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I have a script X that has:
for x = 1:5000
    output{x} = Script_Y(input(:,:,:,x));
end
Script_Y has a particular loop (among other code):
for alpha = 1:(size(input, 3)-1)
    output_preprocessed = Script_Z(input(:,:,alpha), input(:,:,alpha+1));
end
% Later, some more operations are committed on output_preprocessed to give
% the function output.
Script_Z has a loop (among other code):
% Some operations are committed on function inputs to get input_postprocessed_1 and input_postprocessed_2
for k = 1:200
    x = input_postprocessed_1/input_postprocessed_2
    % More steps to make x precise %
end
% Later, some more operations are committed on x to give
% the function output.
It might occur that for some k, input_postprocessed_1 is singular or near-singular and as soon as Matlab throws this warning, I want to skip the particular iteration in the master loop at my script X! For that x, output{x} shall return NULL or nothing - either sufices for me.
How to go about?
2 Comments
  Image Analyst
      
      
 on 28 Sep 2023
				What exactly is the warning?  Please paste back here all the orange or red text that you see when it produces the warning.
  Bruno Luong
      
      
 on 28 Sep 2023
				Actually it input_postprocessed_2 at the right division and the warning is likely the infamous
Warning: Matrix is close to singular or badly scaled. Results may be inaccurate. RCOND =  XXXXXX. 
Accepted Answer
  Bruno Luong
      
      
 on 28 Sep 2023
        
      Edited: Bruno Luong
      
      
 on 28 Sep 2023
  
      Modification of script_Z
for k = 1:200
    lastwarn('',''); % clean the warning state
    x = input_postprocessed_1/input_postprocessed_2;
    [~,warnid] = lastwarn;
    if strcmp(warnid, 'MATLAB:singularMatrix');
        x = []; % I assume this is output_preprocessed returned to script Y
        break
    end
    % More steps to make x precise %
end
script_Y
for alpha = 1:(size(input, 3)-1)
    output_preprocessed = Script_Z(input(:,:,alpha), input(:,:,alpha+1));
    if isempty(output_preprocessed)
        break
    end
end
script_X
for x = 1:5000
    output{x} = Script_Y(input(:,:,:,x));
    % output{x} is empty if the division fails ( input_postprocessed_2is
    % singular)
end
0 Comments
More Answers (1)
  Image Analyst
      
      
 on 28 Sep 2023
        You can use try catch:
for k = 1 : 200
    try
        % In the try block put the code that might throw an error.
    catch ME
        % If you get here an error occurred.
        continue; % To continue with next iteration, or use "break" to exit the loop.
    end
end
1 Comment
  Bruno Luong
      
      
 on 28 Sep 2023
				
      Edited: Bruno Luong
      
      
 on 28 Sep 2023
  
			warning cannot be branched by try/catch, only error can.
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