this code requires more input arguments to run

function [m, A, Eigenfaces] = EigenfaceCore(T)
m = mean(T,2); % Computing the average face image m = (1/P)*sum(Tj's)    (j = 1 : P)
Train_Number = size(T,2);
A = [];  
for i = 1 : Train_Number
    temp = double(T(:,i)) - m; % Computing the difference image for each image in the training set Ai = Ti - m
    A = [A temp]; % Merging all centered images
end

L = A'*A; % L is the surrogate of covariance matrix C=A*A'.
[V ,D] = eig(L); % Diagonal elements of D are the eigenvalues for both L=A'*A and C=A*A'.
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 = A * L_eig_vec; % A: centered image vectors

[Walter Roberson]

How are you invoking the code?

[Kalyan Seelam]

through this code sir..

function T = CreateDatabase(TrainDatabase)
 
TrainFiles = dir('C:\Users\kalyan\Documents\MATLAB\Attendance\TrainDatabase\');
Train_Number = 0;

for i = 1:size(TrainFiles,1)
    if not(strcmp(TrainFiles(i).name,'.')|strcmp(TrainFiles(i).name,'..')|strcmp(TrainFiles(i).name,'Thumbs.db'))
        Train_Number = Train_Number + 1; % Number of all images in the training database
    end
end

% Construction of 2D matrix from 1D image vectors
T = [];
for i = 1 : Train_Number
    
    % I have chosen the name of each image in databases as a corresponding
    % number. However, it is not mandatory!
    str = int2str(i);
    str = strcat(str,'.jpg');
    str = strcat(TrainDatabase,str);
    
    img = imread(str);
    img = rgb2gray(img);
    
    [irow, icol] = size(img);
   
    temp = reshape(img',irow*icol,1);   % Reshaping 2D images into 1D image vectors

    T = [T temp]; % 'T' grows after each turn                    
end

[Kalyan Seelam]

this code also shows requires more arguments

[Walter Roberson]

That code does not have any call to EigenFaceCore; and if it did, there would still be the question of how you invoke this function CreateDatabase ?

[Walter Roberson]

I suspect that you are running the code by pressing the green Run button in the editor. When you do that, how are you expecting MATLAB to know what the value of TrainDatabase or T should be?