How to know seed directly?

Hi,

I use "rng" to know which seed was selected after doing "rng shuffle."

How can I only know the seed directly? I don't need to know "type" and "state."

Thanks!

Answer 1

[Peter Perkins]

Hsinho, you may be asking for this:

>> rng shuffle
>> s = rng
s = 
     Type: 'twister'
     Seed: 1066045100
    State: [625x1 uint32]
>> s.Seed
ans =
  1066045100

[Hsinho]

Thanks!

A further question:

 s=cell(1,n)
 for i=1:n
     rng shuffle;
     s{i}=rng;
 end

In this case, is it possible to rescue the seed from this s cell directly? how?

[Peter Perkins]

1) You are calling rng in a loop. Unless you are doing something specialized, you almost certainly do not need to do that. It may be that you want some kind of reproducibility for each individual iteration of the loop. I strongly recommend that you read the documentation about how to use rng. If that kind of reproducibility is what you are after, especially read the last paragraph, and then perhaps also read this description of substreams etc. But chances are, you do not want to call rng in a loop.

2) s{i}.State

[Hsinho]

Thank you! It's very helpful.

Answer 2

[Greg Heath]

I think it is better to determine the seed before you generate the random numbers. In particular,

Either assign the seed first or determine the current seed before using shuffle.

If you know that you are going to use random numbers, it is convenient to set the seed at the beginning of the program when space and figures are cleared. For example:

close all; clear all; clc;

plt = 0; rng(4151941);

. . .

plt = plt+1; figure(plt);

. . .

Hope this helps.

Greg

[Hsinho]

Thanks for your answer!