Error using - Matrix dimensions must agree. Error in Eigenfaces (line 14) t=double(z(i,:))-m;

function [  ] = Eigenfaces( ) 
z=[];
ta=[];
for ii=1:100
    str=int2str(ii);
    str=strcat(str,'.jpg');
    im=imread(str);
    im=rgb2gray(im);
    im=imresize(im,[256 256]);
    temp=reshape(im,65536,1);
    z=[z temp];m=mean(z,2);
end
for i=1:size(z,2)
    t=double(z(i,:))-m;
    ta=[ta t];
end
R=ta'*ta;    
[v,d]=eig(R);   
L_eig_vec=[];   
for i=1:size(v,2)      
     if(d(i,i)>1)      
         L_eig_vec=[ L_eig_vec ;  v(:,i) ];   
     end   
end    
Eigenfaces = ta*L_eig_vec;
disp('eig finished');
projectedimages = []; 
Train_Number = size(ta,2);
for i = 1 : Train_Number 
     temp = Eigenfaces'*ta(:,i); %he
     projectedimages = [projectedimages temp];
end
target=eye(Train_Number);
save latest.mat
end

Answer 1

[Sulaymon Eshkabilov]

Hi,

Here is the corrected answer for MATLAB 2013 version:

function [  ] = Eigenfaces( ) 
z=[];
ta=[];
for ii=1:100
    str=int2str(ii);
    str=strcat(str,'.jpg');
    im=imread(str);
    im=rgb2gray(im);
    im=imresize(im,[256 256]);
    temp=reshape(im,65536,1);
    z=[z temp]; m=mean(z,2);
 end
for i=1:size(z,2)
    t=double(z(:,i))-m;
    ta=[ta t];
end
 R=ta'*ta;    
 [v,d]=eig(R, R, 'chol'); 
  L_eig_vec=[];   
   for i=1:size(v,2)      
  if(d(i,i)>1)      
      L_eig_vec=[ L_eig_vec ;  v(i,i) ];   
  end   
 end    
  Eigenfaces = ta*L_eig_vec;
     disp('eig finished');
 projectedimages = []; 
Train_Number = size(ta,2);
 for i = 1 : Train_Number 
temp = Eigenfaces'*ta(:,i); 
 projectedimages = [projectedimages temp];
end
target=eye(Train_Number);
save latest.mat
end

Good luck.

Answer 2

[Geoff Hayes]

Bereket - the error message is telling you that the matrices upon which you are executing the difference (of), are of different dimensions. When subtracting one matrix from an another, both must have the same number of rows and columns. In the case of your code

t=double(z(i,:))-m;

what are the dimensions of z(i,:) compared with the dimensions of m? Or are you expecting m to be a scalar?

Also, you have a line of code

Eigenfaces = ta*L_eig_vec;

where Eignefaces is the name of your function. Is this intentional? Or should this just be local variable named differently from the function?