MATLAB: Nested loop will not enter second iteration

nest loop

Hi,
Below is my code. For each month of each year I am trying to get the average and std for a set of values. The first iteration works for the first year. But then it does not continue. Can someone tell me where the problem is.
[M,ia,ic] = unique(CO2_FFD(:,2)); %find unique years, M = unique year, ia = row with unique year
m=[1;2;3;4;5;6;7;8;9;10;11;12];%set an array for 12 months
CO2_YM_averages = zeros(length(M)*12,2); %array for averages & std's, size of year*12months
for i=1:length(M)
yrows = find(M(i)==CO2_FFD(:,2)); %find rows where year is equal to M(i)
for j=1:length(m)
mrows=find(CO2_FFD(yrows,3)== m(j));%find rows where month = m(i)
CO2_YM_averages(j,1) = mean(CO2_FFD(mrows,8)); %average data for each month
CO2_YM_averages(j,2) = std(CO2_FFD(mrows,8)); %std data for each month
end
end

Best Answer

I get 3 tierations for i. Here is my code:
% here is some sample data:
CO2_FFD = [0  2000  1  1  0  0  0  340  ;
0  2000  1  2  0  0  0  380  ;
0  2000  2  3  0  0  0  280  ;
0  2000  2  4  0  0  0  450  ;
0  2000  3  5  0  0  0  330  ;
0  2000  3  6  0  0  0  450  ;
0  2000  4  7  0  0  0  380  ;
0  2000  4  8  0  0  0  290  ;
0  2000  5  9  0  0  0  340  ;
0  2000  5  10  0  0  0  380  ;
0  2000  6  11  0  0  0  280  ;
0  2000  6  12  0  0  0  450  ;
0  2000  7  13  0  0  0  330  ;
0  2000  7  14  0  0  0  450  ;
0  2000  8  15  0  0  0  380  ;
0  2000  8  16  0  0  0  290  ;
0  2000  9  17  0  0  0  340  ;
0  2000  9  18  0  0  0  380  ;
0  2000  10  19  0  0  0  280  ;
0  2000  10  20  0  0  0  450  ;
0  2000  11  21  0  0  0  330  ;
0  2000  11  22  0  0  0  450  ;
0  2000  12  23  0  0  0  380  ;
0  2000  12  24  0  0  0  290  ;
0  2001  1  25  0  0  0  340  ;
0  2001  1  26  0  0  0  380  ;
0  2001  2  27  0  0  0  280  ;
0  2001  2  28  0  0  0  450  ;
0  2001  3  29  0  0  0  330  ;
0  2001  3  30  0  0  0  450  ;
0  2001  4  1  0  0  0  380  ;
0  2001  4  2  0  0  0  290  ;
0  2001  5  3  0  0  0  340  ;
0  2001  5  4  0  0  0  380  ;
0  2001  6  5  0  0  0  280  ;
0  2001  6  6  0  0  0  450  ;
0  2001  7  7  0  0  0  330  ;
0  2001  7  8  0  0  0  450  ;
0  2001  8  9  0  0  0  380  ;
0  2001  8  10  0  0  0  290  ;
0  2001  9  11  0  0  0  340  ;
0  2001  9  12  0  0  0  380  ;
0  2001  10  13  0  0  0  280  ;
0  2001  10  14  0  0  0  450  ;
0  2001  11  15  0  0  0  330  ;
0  2001  11  16  0  0  0  450  ;
0  2001  12  17  0  0  0  380  ;
0  2001  12  18  0  0  0  290  ;
0  2002  1  19  0  0  0  340  ;
0  2002  1  20  0  0  0  380  ;
0  2002  2  21  0  0  0  280  ;
0  2002  2  22  0  0  0  450  ;
0  2002  3  23  0  0  0  330  ;
0  2002  3  24  0  0  0  450  ;
0  2002  4  25  0  0  0  380  ;
0  2002  4  26  0  0  0  290  ;
0  2002  5  27  0  0  0  340  ;
0  2002  5  28  0  0  0  380  ;
0  2002  6  29  0  0  0  280  ;
0  2002  6  30  0  0  0  450  ;
0  2002  7  31  0  0  0  330  ;
0  2002  7  32  0  0  0  450  ;
0  2002  8  33  0  0  0  380  ;
0  2002  8  34  0  0  0  290  ;
0  2002  9  35  0  0  0  340  ;
0  2002  9  36  0  0  0  380  ;
0  2002  10  37  0  0  0  280  ;
0  2002  10  38  0  0  0  450  ;
0  2002  11  39  0  0  0  330  ;
0  2002  11  40  0  0  0  450  ;
0  2002  12  41  0  0  0  380  ;
0  2002  12  42  0  0  0  290  ]
[M,ia,ic] = unique(CO2_FFD(:,2)); %find unique years, M = unique year, ia = row with unique year
m=[1;2;3;4;5;6;7;8;9;10;11;12];%set an array for 12 months
CO2_YM_averages = zeros(length(M)*12,2); %array for averages & std's, size of year*12months
for i=1:length(M)  
  fprintf('i = %d\n', i);
  yrows = find(M(i)==CO2_FFD(:,2)); %find rows where year is equal to M(i)  
  for j=1:length(m)    
  fprintf('    j = %d\n', j);
    mrows=find(CO2_FFD(yrows,3)== m(j));%find rows where month = m(i)    
    CO2_YM_averages(j,1) = mean(CO2_FFD(mrows,8)); %average data for each month    
    CO2_YM_averages(j,2) = std(CO2_FFD(mrows,8)); %std data for each month    
  end  
end
and here is the results:
i = 1
    j = 1
    j = 2
    j = 3
    j = 4
    j = 5
    j = 6
    j = 7
    j = 8
    j = 9
    j = 10
    j = 11
    j = 12
i = 2
    j = 1
    j = 2
    j = 3
    j = 4
    j = 5
    j = 6
    j = 7
    j = 8
    j = 9
    j = 10
    j = 11
    j = 12
i = 3
    j = 1
    j = 2
    j = 3
    j = 4
    j = 5
    j = 6
    j = 7
    j = 8
    j = 9
    j = 10
    j = 11
    j = 12
Why do you say there is only one iteration for i???
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