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

How can I preallocate matrix t:

t=[];

for i=1:3;
    a=randi(10,3,2);

      t=[a t];

end

Answer 1

[the cyclist]

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

[Giorgos Papakonstantinou]

Thank you cyclist.