In that case you have two options.....
1. Option 1
Go for saving the data into cell .
m = 10 ;
iwant = cell(m,1) ;
for i = 1:m
iwant{i} = rand(randperm(100,1),1) ;
end
2. Option 2
Append NaN/ zeroes to extra data
m = 10 ;
n = 10 ;
iwant = NaN(m,n) ;
for i = 1:m
k = randperm(8,1) ;
iwant(i,1:k) = rand(1,k) ;
end
