I have this error : Reference to non-existent field 'mat'.

here is the code, I wanted to split the database into training and testing subsets. the error appears ince I run this : observation=dB.mat(k,:); in the code below

function [TrainDBN , TestDBN]=genererDB(dB,Pourcentage_Test)
mapping=getmapping(8,'u2');

V=[];
database=[];

% number of features
dB.classes=[];
classes=[];
dB.Nbofclasses=50;%number of classes 
Pourcentage_Test= 0.3;
Pourcentage_Training= 70/100;
for i=1:50
    for j=1:15
        name=['S' num2str(i,'%02d') '_' num2str(j,'%02d') '.jpg'];
        img=imread(name);
        imgHist =lbp(img,1,8,mapping,'nh'); 
        database=[database;imgHist]; 
        imshow(img);
        dB.NbImagesPerClass(i)=15;
        classes=[classes;i];
        dB.mat=database;
        dB.classes=classes;
        pause
    end  
J=randperm(dB.NbImagesPerClass);
for L=1:length(J)
    if J(L)<=Pourcentage_Test*dB.NbImagesPerClass/100;
        J(L)=0;
    else
        J(L)=1;
    end
V=[V J];
end
V=V';

TrainDBN.mat=[];
TestDBN.mat=[];

TrainDBN.classes=[];
TestDBN.classes=[];

% Générer les bases d'apprentissage TrainDBN et de test TestDB
for k=1:length(V)
    observation=dB.mat(k,:);
    if(V(k)==1)
        TrainDBN.mat=[TrainDBN.Mat; observation];
        TrainDBN.classes=[TrainDBN.classes;dB.classes(k)];
    else
        TestDBN.mat=[TestDBN.mat; observation];
        TestDBN.classes=[TestDBN.classes;dB.classes(k)];        
    end
end

TrainDBN.NbClasses=dB.Nbclasses;
TestDBN.NbClasses=dB.Nbclasses;
end

[EDITED, Jan, please use a proper code formatting - thanks]

Answer 1

[Jan]

The variable dB.mat is created in the loop. It is strange, that it is missing later on. Therefore I suggest to use the debugger to find out, what's going on. E.g. type this in the command line:

dbstop if error

Then run the code again. When it stops at the error, inspect the contents of the variable dB.

Perhaps you did not save the code after you've edited it?