It is best to pre-allocate your output array as close to the size you think you need, because extending a matrix hurts performance substantially.
cols=2;
est_rows=5;%estimate of the largest number of rows
result=zeros(est_rows,cols);keep_rows=0;
for col=1:2
if col==1 ,part_result=(1:2).';
elseif col==2,part_result=(1:3).';
end
keep_rows=max(keep_rows,numel(part_result));
result(1:numel(part_result),col)=part_result;
end
result((keep_rows+1):end,:)=[];%will only crop unused rows
result
