MATLAB: Preallocating the size of a matrix which concatenates horizontally matrices in a for loop

Question

How can I preallocate matrix t:

t=[];
for i=1:3;
    a=randi(10,3,2);
      t=[a t];
end

Answer 1

Like this. (I also parameterized so it would be easier to see how this generalizes.)

m=3;
n=2;
t = zeros(m,m*n);
for i=1:m;
    a = randi(10,m,n);
    t(:,n*(i-1)+1:n*i) = a;
end

You don't need the intermediate variable, either:

m=3;
n=2;
t = zeros(m,m*n);
for i=1:m;
    t(:,n*(i-1)+1:n*i) = randi(10,m,n);
end