Question

How do I distribute probability randomly over n values in matlab?
If I have 128 vectors.
I want to assign a random probabilty to all of them such that the sum of all of them equals to 1.

e.g.
n=4
p1=0.37
p2=0.21
p3=0
p4=0.42

Answer 1

You can just divide the vector by the sum of it’s elements. For example, for a vector of length 4 you can do:

>> v = rand(4, 1);
>> v = v/sum(v)

v = 
    0.2951
    0.3281
    0.0460
    0.3308

>> sum(v)

ans = 

    1.0000

Note, I am assuming you want uniformly distributed numbers, since you don’t state what distribution you want in the question.