dimension mismatch error

clc;
clear all;
allsamples=[];
for i=1:6
    tic
        a=imread(strcat('C:\Users\user\Documents\MATLAB\face','\',num2str(i),'.jpg'));
        imshow(a);
        b=a(1:112*92);
        b=double(b);
        allsamples=[allsamples;b];
        toc
end
samplemean=mean(allsamples);
xmean=zeros();
for i=1:200
    xmean(i,:)=allsamples(i,:)-samplemean;
end

from the above program i got the error message as

??? Subscripted assignment dimension mismatch.

Error in ==> example1 at 16
    xmean(i,:)=allsamples(i,:)-samplemean;

how to clear this error plz help me

Answer 1

[Andrei Bobrov]

pre-allocation:

xmean = zeros(200,size(allsamples,2));

OR:

xmean = bsxfun(@minus,allsamples(1:200,:),mean(allsamples));