t=0.1;Ang_1 = [10 20 30 45 80];% this vector of options
Since your for loop had invalid syntax and you don't use what I suspect you intended to be the loop variable (i) inside the loop I commented it out.
%for i:1:1
prob = (exp((1/t)*1.2*10^-5))./(exp((1/t)*1.2*10^-4)) % this is probability could be changable each eteration
select = Ang_1(find(rand<cumsum(prob),1)) % select angle according to "prob"
%end
Since prob is a scalar, cumsum(prob) is just prob itself. So that find call will return either 1 or [] depending on whether rand generated a number less than prob or not.
If you had a vector of probabilities, like this which uses the value in Ang_1 as the relative frequency of the value:
probabilities = [0 cumsum(Ang_1)./sum(Ang_1)]
then you could use discretize to generate your list.
x = rand(10, 1);
values = discretize(x, probabilities, Ang_1);
Another way to generate these values is as categories.
categories = discretize(x, probabilities, 'categorical');
Let's summarize the results in a table.
results = table(x, values, categories)
