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

for loopmatrix manipulationpreallocate

How can I preallocate matrix t:
t=[];
for i=1:3;
a=randi(10,3,2);
t=[a t];
end

Best Answer

  • 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