When you compute:
lower_limit = 0.1;
%define the upper limit
higher_limit = 0.9;
x = lower_limit:higher_limit
The vector x contains the values from lower_limit to higher_limit using a step size of 1. How many times do you need to add 1 to 0.1 to reach 0.9 (if you go past 0.9, remove the points past 0.9, leaving only the points that are less than or equal to 0.9)?
If you want to use a smaller step size, specify it when you create the vector.
step_size = 0.1;
x = lower_limit:step_size:higher_limit
As for the rest of your code, you don't want to use randi for this application. randi generates random numbers with replacement, like you were rolling a die. The randperm creates a random permutation of numbers between 1 and the limit you specify as input, as though you were shuffling a deck of cards. Assuming a standard deck, the Queen of hearts (for one example) can only be in one place, but if I roll a six-sided die four times I could end up with two 3's, a 5, and a 6.
dieSides = 6;
numRolls = 4;
dieRolls = randi(dieSides, 1, numRolls)
deckSize = dieSides;
numCards = numRolls;
cardOrder = randperm(deckSize, numCards)
