You want to generate a random number of random numbers? With an additional constraint that all are greater than 0.5? This is far esier than you think. (You had an unnecessary pair of parens in your code.)
So that generate a random length vector of uniform random numbers between 0 and 1. But if you wanted to have all of them be numbers between .5 and 1, this is easy.
r1 = (1 + rand(randi(10),1))/2;
So adding 1 to a number between 0 and 1 makes it lie between 1 and 2. If you then divide by 2, it will fall always betweem .5 and 1.
The result is a vector of random length, where all lie between .5 and 1.