MATLAB: Concatenating vectors generated with loop


I would like to run a for loop like
for i=1:N
output=[1 i]
output2 = [output2 output]
But in this example it seems that I need to define output2 at the beginning. Is there any compact way to write this operation?

Best Answer

Hi alpedhuez, define output2 by putting
output2 = [];
just before the do loop.
Unless you are using the intermediate results somehow, concatenation in this manner is not recommended. For N = 10000 or less it's all right in terms of execution time. But with execution time growing rapidly, eventually it makes more sense (and is better practice anyway) to define an array by output2 = ones(1,2*N) and then fill all the even entries with output2(2:2:2*N) = 1:N