for i = 1:nclass,%1 inx_i = find(class== Numclass(i));%2 Xki = Vector(:,inx_i);%3 Dki = DW(:,inx_i);%4 sum(Dki); %5 M(i,:)=sum(Dki*Xki');%6 meanclass(i) = Numclass(i); %7end in this code meaning of 3rd n 4th line, n can we use ',' after for

for i = 1:nclass,%1  
 inx_i = find(class== Numclass(i));%2
   Xki = Vector(:,inx_i);%3  
Dki = DW(:,inx_i);%4   
sum(Dki); %5  
M(i,:)=sum(Dki*Xki');%6
  meanclass(i) = Numclass(i); %7
end

in this code meaning of 3rd n 4th line, n can we use ',' after for loop? line number 6th means that every ith row of M will store sum of product of Dki and Xki ??

Answer 1

[KSSV]

for i = 1:nclass,%1 
    inx_i = find(class== Numclass(i));%2 
    Xki = Vector(:,inx_i);%3 Extracting the column inx_i from matrix Vector
    Dki = DW(:,inx_i); %4 Extracting the column inx_i from DW
    sum(Dki); %5 
    M(i,:)=sum(Dki*Xki');%6 Dki*Xki' will be a matrix, sum(Dki*Xki') results into a array
    meanclass(i) = Numclass(i); %7 
end
% in this code meaning of 3rd n 4th line, n can we use ',' after for loop? 
% line number 6th means that every ith row of M will store sum of product of Dki and Xki ??

I suggest you to run the code and use debugging option. When you put debugging point, your code will stop at the point and you can check the dimensions of every variable of the code. Read about debugging matlab code.