simulink random sequence generation

Hi,

I just created a "Malab function" block in simulink, and it generates random numbers. The problem now is that the sequence repeats whenever I run the simulation. The matlab function block simply looks like this function y=fcn() y=randn;

i know the seed should be reset but not sure how. Thanks

Answer 1

[Kaustubha Govind]

According to the documentation for randn, you need to use the function rng to control the seed, etc. You may want to look into that.

Answer 2

[Shashank Prasanna]

Random numbers in all software are pseudorandom sequence of numbers. As Kaustubha already mentioned you will have to seed your random number generator differently if you don't want reproducibility (Which would be required if you want to run the simulation in the exact same way)

Include the following command at the very beginning of your matlabfunction block:

rng('shuffle')

This will choose a random seed every time.

http://www.mathworks.com/help/matlab/ref/rng.html

Answer 3

[amin re]

Note that I'm using a matlab function block in a simulink, that doesn't work when I use rng shuffle in the function. so basically it looks like

function y=fcn()

rng shuffle

y=rndn

however i get this error The 'shuffle' input is only supported for Mex targets with the ExtrinsicCalls option.

[Kaustubha Govind]

Amin: Do you plan to generate standalone C/C++ code from your model? If not, you can call the function by declaring it extrinsic as the error suggests:

function y=fcn()
coder.extrinsic('rng');
rng('shuffle');
y=rndn;