for loop in a function

 %function [temp_finalmean]=first_difference_mean
%calculate the first difference between two column
files=dir('*.mat');
temp_save=zeros(30,359);
for m= 1:length(files)
    load(files(m).name)    
    temp_temp=zeros(30,359);
    temp_thickness=cell2mat(T(1,1));
    temp_thickness=image2polar(temp_thickness,peaks(1,1)*200/668,peaks(2,1)*200/668,'counterclockwise',[],1,pi/180,'linear');
    temp_size=size(temp_thickness);
    temp_thickness(62:temp_size(1),:)=[];
    temp_thickness(1:31,:)=[];
    disp(['Loading ' num2str(m) ' files'])
    for n=1:359
        for k=1:30
            temp_temp(k,n)=temp_thickness(k,n+1)-temp_thickness(k,n);
        end
    end
    temp_save=temp_save+temp_temp;
end
    temp_finalmean=temp_save/length(files);
end

If I remove the top line and bottom line(i.e. the function and end),then I will have my code run perfectly. I mean I can get different result from the same code, it is strange... Is it I can't use load() in a function or something happened?

Thank you

Answer 1

[Walter Roberson]

When you have end matching function then you are creating a static workspace where it is not permitted to "poof" variables into existence using eval() or assignin() or evalin() -- and so, indirectly, also not using load() or syms() . You should use the output form of load() and pull the required information out of the structure that is returned.

[Marco Yu]

Can you use this as a example to correct the problem please?

[Walter Roberson]

function temp_finalmean = first_difference_mean
  %calculate the first difference between two column
  files = dir('*.mat');
  temp_save = zeros(30,359);
  for m = 1 : length(files)
      data = load(files(m).name);     %*
      temp_temp = zeros(30,359);
      temp_thickness = cell2mat( data.T(1,1));  %*
      temp_thickness = image2polar(temp_thickness, data.peaks(1,1)*200/668, data.peaks(2,1)*200/668, 'counterclockwise', [], 1, pi/180, 'linear');  %*
      temp_size = size(temp_thickness);
      temp_thickness(62:temp_size(1),:) = [];
      temp_thickness(1:31,:) = [];
      disp(['Loading ' num2str(m) ' files'])
      temp_temp = diff( temp_thickness(1:30, 1:360), [], 2 );
      temp_save = temp_save + temp_temp;
  end
  temp_finalmean = temp_save / length(files);
end

The lines marked with %* are the essential changes; the other changes are style or efficiency (replacing the double loop with a single diff)

[Marco Yu]

Thank you so much :D you are an expert