rand() gives the same values in each run

Hi

I'm working on the evaluation of metaheuristic algorithms and i need to test each technique in many runs, however the rand() function always generates the same random values in each run, which is not good for the evaluation.

For example, if rand()=0.56 in the 1st run at the 2nd iteration, then rand()=0.56 for all the other runs at the second iteration.

[Rik]

Does your code set a random seed anywhere?

[Hamza Belm]

I didn't use rng anywere in my code, i've just used rand() by default directly.

here is an example

v(u)= w*v(u)+(c1*rand()*(pbest(u)-dcur(u)))+(c2*rand()*(gbest-dcur(u)));

this is the only line where rand() is used

Answer 1

[Steven Lord]

Are you initializing the random number generator with rng too frequently or in the wrong place in your code flow?

[Hamza Belm]

I didn't use rng anywere in my code, i've just used rand() by default directly.

here is an example

v(u)= w*v(u)+(c1*rand()*(pbest(u)-dcur(u)))+(c2*rand()*(gbest-dcur(u)));

this is the only line where rand() is used

[Steven Lord]

Show a full (small) segment of code that we can run that demonstrates the behavior you described.