matlab R2020b randperm fuction is not random

Hi,

When I use matlab R2020b on linux platform, commands follow：

order = randperm(10)

disp(order)

results show:

6     3     7     8     5     1     2     4     9    10

6     3     7     8     5     1     2     4     9    10

Curiously, the result is fixed，i.e., when I run this script again, the same results appear. Does anybody know what's wrong? thanks

[Torsten]

order = randperm(10)

order = 1×10

1 9 10 2 5 6 4 8 7 3

order = randperm(10)

order = 1×10

8 3 9 7 1 6 2 5 10 4

Doesn't look fixed to me.

See

https://de.mathworks.com/help/matlab/ref/rng.html

for details on how to define the seed for the random generator (which can also be used to get different outputs if the script is executed several times (rng('shuffle'))).

[Adam Danz]

Make sure you're using MATLAB's randperm function by using which

which randperm

built-in (/MATLAB/toolbox/matlab/randfun/randperm)

Does the same result occur if you shuffle the random number generator?

randperm(10)

rng('shuffle')

randperm(10)

[俊 马]

thanks， it worked

Answer 1

[Fangjun Jiang]

Duh! You store the result in "order" and display it again. Of course they are the same!

order = randperm(10)

order = 1×10

5 7 6 10 3 1 4 9 2 8

disp(order)

     5     7     6    10     3     1     4     9     2     8

order = randperm(10)

order = 1×10

6 7 5 10 3 8 1 2 9 4

disp(order)

     6     7     5    10     3     8     1     2     9     4

[Adam Danz]

Ha! Good catch!