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How do I set a seed to generate different random initial numbers and storing them

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Samson
Samson on 2 Jul 2020
Commented: Samson on 9 Jul 2020
for kk = 1 : Iter
xD = rand(N,1)*2*pi; % Init Cond. Driver
end

  3 Comments

Wiley Mosley
Wiley Mosley on 3 Jul 2020
I think you are wanting a random repeatable setup.
I think the best way to set that up is to review:
Essentially you need to set a random repeatable seed so that you can reinitialize and run with the same random values for refining your code.
rng(1,'twister');
Samson
Samson on 3 Jul 2020
Thank you for your response. However, I do not want the numbers to be repeated. I need to run a100 realizations and having 100 different initial conditions and storing up the initial conditions so I can retrieve any to work

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More Answers (1)

Wiley Mosley
Wiley Mosley on 3 Jul 2020
Edited: Wiley Mosley on 3 Jul 2020
rng(1,'twister'); % init generator for random repeatable with seed 1
s = rng; % save generator settings as s
for kk = 1: Iter
xD = rand (N, 1) * 2 * pi; % Init Cond. Driver
end
disp(xD) %just to print out your xD values
rng(s) % Reset the generator
for kk = 1: Iter
xD = rand (N, 1) * 2 * pi; % Init Cond. Driver
end
disp(xD) %printing out the xD values again should show that they match
I believe somthing like this should help you.

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Walter Roberson
Walter Roberson on 8 Jul 2020
Iter = 100;
rstates = cell(Iter,1);
for kk = 1 : Iter
rstates{kk} = rng(); %record current rng
xD = rand(N,1)*2*pi; % Init Cond. Driver
[t_IF, t_FS, zVals] = changesN_TestChaosMain( N, G, alphaD, omegaD, xD, NumberWindows, WindowLength, dt);
lifetimes(kk) = t_FS - t_IF;
end
Later if you wwant to look at xD for iteration #17, then
rng(rstates{17});
xD = rand(N,1)*2*pi; % same random values used for iteration #17
Samson
Samson on 8 Jul 2020
Hello Walter, thank you so much for this simplified version. However, I did run the N=50 oscillators 5 times, that is iter=5 as a sample. on using rng(rstates{4}); to run and do some plot, my results is below:
for kk = 1 : Iter
%rstates{kk} = rng();
rng(rstates{4});
xD = rand(N,1)*2*pi; % Init Cond. Driver
%%% Function Call
[X,t_IF, t_FS, zVals] = changesN_TestChaosMain( N, G, alphaD, omegaD, xD, NumberWindows, WindowLength, dt);
lifetimes(kk) = t_FS - t_IF;
I got the error below:
Error using rng (line 133)
First input must be a nonnegative integer seed less than 2^32,
'shuffle', 'default', or generator settings captured previously
using S = RNG.
Error in changesN_testcall1 (line 92)
rng(rstates{4});
Samson
Samson on 9 Jul 2020
Hello Walter, thank you so much. You were so helpful. I used the following code and it gave me what I needed. However, in case of having the same random numbers, use rng('shuffle'). I have two questions now>
  • In running iteration #40 for instance with same initial conditions, what should I do precisely use the same initial conditions from my code below. I was thinking I have to put the initial values of #40 into the function and run the simulation but do not know how to do it. Kindly show me please.
  • How the I plot the lifetimes of #40 using histogram. Should I say in the command window,
H= histogram(lifetimes(40))?
Iter = 100;
lifetimes = zeros(1,Iter);
for ii = 1: length(omegaDArr) % omega_D iterated
omegaD = omegaDArr(ii);
%%% Repeated Simulations of each pair (DeltaOmega, Epsilon)
xDR = zeros(N,Iter);
for kk = 1 : Iter
xD = rand(N,1)*2*pi; % Init Cond. Driver
xDR(:,kk) = xD ;
%%% Function Call
[X, t_IF, t_FS, zVals] = changesN_TestChaosMain( N, G, alphaD, omegaD, xD, NumberWindows, WindowLength, dt);
end

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