how to use a variable created inside the for loop, outside the loop?

My code:

path11='C:\Users\Avani\Documents\MATLAB\sift_COREL_101';
eu_files=dir('C:\Users\Avani\Documents\MATLAB\sift_COREL_101');
eu_files1=dir('C:\Users\Avani\Documents\MATLAB\sift_event_img');
value1=1;
for abc=3:length(eu_files);
  infiles=dir(fullfile('C:\Users\Avani\Documents\MATLAB\sift_COREL_101\',eu_files(abc).name));
  for def=3:length(infiles)
    str=strcat(path11,'\',eu_files(abc).name,'\',infiles(def).name);
    s=load(str);
    for row=1:217
      value=1;
      sum=0;
      for colu=1:6
        matrix(value)=s(1).Keypoint(1,colu)-Keypoint(row,colu);
        value=value+1;
      end
      for val=1:length(matrix)
        sum=sum+matrix(val);
      end
      finalval(row)=sum;
    end
    
    for len=1:length(finalval)
      for len1=1:length(finalval)
        for len2 =len1:length(finalval)
          if finalval(len1)>finalval(len2)
            temp=finalval(len1);
            finalval(len1)=finalval(len2);
            finalval(len2)=temp;
          end
        end
      end
    end
  end
  
  if(finalval(1)>0.3 && finalval(1)<0.7)
    finalmatrix(value1)=finalval(1);
    finalmatrix(value1).label=eu_files(abc);
    finalmatrix(value1).class='COREL_101';
    value1=value1+1;
  end
end

[Walter Roberson]

It is not a good idea to use a variable named "sum" !

[Image Analyst]

Which variable do you want to use outside of a for loop? Which for loop is the variable in? Why can't you use it outside? Have you tried?

[Avani]

i have to use finalmatrix outside the for loop.. the variable is in for def=3:length(...). yes sir i have tried using it outside the loop.. an error occured...

Answer 1

[Image Analyst]

OK, and why can't you use finalmatrix outside the loop? What happens when you try?

[Avani]

an error occurs... the err is: Undefined function or variable "finalmatrix".

Answer 2

[Image Analyst]

Then the problem is in this line:

if(finalval(1)>0.3 && finalval(1)<0.7)

Evidently this if statement never becomes true so finalmatrix never gets assigned.

http://blogs.mathworks.com/videos/2010/09/02/using-debugger-to-walk-through-code/

[Walter Roberson]

Also, before the loop, initialize

finalmatrix = [];

Then if there are no files to be read, the variable will still be defined.