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Why does MATLAB generate identical random values after re-opening the program?

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I run the code below
y = rand(1,5)
and I get the following values:
0.8147 0.9058 0.1270 0.9134 0.6324
I close MATLAB and reopen it again and enter the same code and I get the same random values. Why does MATLAB create the exact same numbers each time?
  1 Comment
Stephen23
Stephen23 on 24 Jul 2018
Edited: Stephen23 on 24 Jul 2018
"Why does MATLAB create the exact same numbers each time?"
Because:
  • computers can't really generate random numbers.
  • that is exactly what MATLAB is specified to do:

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Accepted Answer

Rightia Rollmann
Rightia Rollmann on 24 Jul 2018
I set rng to 'default', so I expected that it'll generate new random numbers after re-running MATLAB, but that is not the case. Why? How can I get MATLAB to generate new random numbers after re-opening it?
  2 Comments
Guillaume
Guillaume on 24 Jul 2018
Follow the link in Stephen's comment to get the answer to your question, or do what Madhan told you.
Also, don't use the answer box for comments.
Stephen23
Stephen23 on 25 Jul 2018
Edited: Stephen23 on 25 Jul 2018
"I set rng to 'default', so I expected that it'll generate new random numbers after re-running MATLAB..."
The rng documentation explains that the 'default' option as "This way, the same random numbers are produced as if you restarted MATLAB. The default settings are the Mersenne Twister with seed 0." Clearly with the same seed it will generate exactly the same values each time. That is what it is specified to do!

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More Answers (1)

madhan ravi
madhan ravi on 24 Jul 2018
Edited: madhan ravi on 24 Jul 2018
hi, see the link below:
https://www.mathworks.com/help/matlab/ref/rng.html

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