how to do constraints for generate random numbers?

Hello, I want to generate x random numbers from 1 to 8760 hours with the constraints x1<x2<x3 and x3 is greater or equal than 8760. I wrote the programming like below but it does not work. Thank you.

clear; clc;
count=1; kira=1; 
while count <= 30; % maximum of 100 random numbers will be generated 
   % the following program is used to generate 20 random numbers 1 at a time
   % everytime a random number is generated,fitness will be calculated
   % if there is a constraint (fitness cannot be calculated), new random
   % number will be generated
   while kira <= 20; % 20 populations are required during initialization

x1=rand(20,1)*8759+1; % generate number from 1 to 8760
x1=round(x1);

x2=rand(20,1)*8759+1;
x2=round(x2);

x3=rand(20,1)*8759+1;
x3=round(x3);
count;

      if x1<x2<x3 & x3<=8760;
          kira = [x1 x2 x3]    
      else
          count=count+1;

          if kira == 21
              return
          end
      end
     end
  end

[John D'Errico]

Make up your mind. In one place, you say that x3 is greater than or equal to 8760, and in another, you say that x3 is <= 8760. In another place, you say that x3 is bounded in the interval [1,8760].

To me, this says that x3 == 8760. I never know with that new math stuff they keep teaching though.

[pfb]

you should consider using "randi".

I'm not sure about your constraints either.... Also, please, format your code properly.

Should your random number be ordered? Why don't you just generate the and then order them?

[Guillaume]

I don't understand why you can't generate 3 random integers within your range and then sort them to ensure they are in the right order. Why discard them if they're not in the order you want?

Answer 1

[John D'Errico]

I'll assume that your goal is merely to generate 3 random numbers from the interval [1,8760], such that all three of them are in increasing order.

The statement that x3 is <= 8760 is irrelevant. We already know that x3 lies in the closed interval [1,8760], so that is implicit in the first statement.

The following single statement does what you appear to be asking for.

A = sort(rand(20,3)*8759 + 1,2);

Having said that, the requirement that they lie in the interval [1,8760] suggests that very possibly your response will be that they must be integers. I know, I should have been able to read your mind. You did round them after all in the snippet of code you wrote. So to generate integers instead, just use randi instead of rand.

A = sort(randi([1,8760],20,3),2);

Next, you will probably return and say, that oh, you need them to be sampled without replacement, so that no replicates are allowed. If that is what you need, then you should say that in the first place. Or if x3 really was going to be forced to 8760 all the time, then you should have said so.

[EDA AZUIN OTHMAN]

hello john, thank you for your comment. yes, I want to generate the 3 random numbers in increasing order. the problem is, it does not generate increasingly for 20 population numbers. can I have a solution for this? thank you. below is the output that I got when I wrote the suggested code by you:

287 1520 8336

3425 4917 8062

462 7283 7725

5862 6464 7038

531 1669 2358

3232 3498 3705

4036 4616 4800

3652 8258 8599

1371 3660 5754

5501 7495 8612

2558 2641 5648

3297 3782 6142

137 1673 5837

3752 4723 8620

1465 4223 6116

931 1057 5839

1561 3263 5164

1122 1736 1982

3370 4290 8752

1500 2975 5107

what I want is the number of x1 is not greater than x2 and x3 for the whole output. Hope you can help me. Thank you

[Michael Haderlein]

Did you try the code suggested in John's answer?

[EDA AZUIN OTHMAN]

Micheal, yes I tried and this is the output that I got.

Answer 2

[Guillaume]

what I want is the number of x1 is not greater than x2 and x3 for the whole output. Hope you can hep me. Thank you

Then why can't you just generate 20x3 = 60 numbers sort them and reshape in three columns?

A = reshape(sort(randi([1 8760], 1, 20*3)), 20, 3)

If you want to then reorder the rows randomly:

A = A(randperm(size(A, 1)), :)

If that's not what you want, then you need to explain yourself much better.

[EDA AZUIN OTHMAN]

thank you Guillaume, I got it.