how to assign random numbers that add up to equal 1

I want to have a,b,c, and d all be random numbers greater than 0. I need a>bcd and b>cd. I also need the numbers to add up to 1. Is there anyway I can do this?

Answer 1

[Walter Roberson]

File Exchange, Roger's randfixedsum() and sort in descending order.

[John D'Errico]

+1. but with a minor flaw: Note that c > d is not required by the problem statement. As such the set

[0.4, 0.3, 0.1, 0.2]

Should be allowed. So if the goal is purely that a > bcd and b > cd, then you need to randomly shuffle the two smallest elements after the sort to gain a truly valid set that will satisfy the requirements and sample the entire space uniformly.