How to use parfor

The original code is as follows, which I would like to convert to parallel using "parfor"

    for rownum=1:rows
    for size=1:half
        flip=cols-size+1

        o1=original(rownum,flip,1);
        o2=original(rownum,flip,2);
        o3=original(rownum,flip,3);
        original(rownum,flip,1)=original(rownum,size,1);
        original(rownum,flip,2)=original(rownum,size,2);
        original(rownum,flip,3)=original(rownum,size,3);

        original(rownum,size,1)=o1;
        original(rownum,size,2)=o2;
        original(rownum,size,3)=o3;
    end  
    end

Help needed, Thanks in advance.

Answer 1

[OCDER]

Are you trying to flip the matrix along the 2nd dimension?

original = flip(original, 2)

Can't do parfor in your case because the indexing to original is inconsistent within the for loops, as in you cannot do this:

 parfor j = 1:3
    for k = 1:3
       A(j, k) = -1;     %MATLAB: got it, will refer to A via A(j, k) indexing
       A(j, 3-k+1) = -2; %ERROR! A must be referred to via same index schemes
                         %Must use A(j, k) all the way through inside parfor
    end
 end

Also, do not override matlab built-in functions such as flip and size, as this will cause issues. To learn more about these, type this in your command window:

>> help size
>> help flip

To prevent overriding MATLAB functions accidentally, use variable names starting with Capital letters EX:

for Size = 1:half  %OK! Size will not override size.m
   ...
end