How to enable parallel computing?

Hi, I'm trying to improve fsolve execution with parallel computing, by implementing this instruction:

options = optimoptions('fsolve','Display','none','Algorithm','trust-region','UseParallel',true);

However, I get this warning during each iteration:

Warning: Unable to create a parallel pool. Continuing with evaluations in serial. To avoid this warning, set the 'UseParallel' option to false.

I think it's possible to use parallel computing, since I'm using a 4 core CPU (AMD Ryzen 5 3500U). I tried to enable all cores manually, but the warning persists.

How to solve it? Thank you!

[Rik]

Do you have the Parallel Computing Toolbox?

[Jan]

What does this mean: " I tried to enable all cores manually"?

[Elia Paini]

I enabled all cores "manually" with Windows msconfig.

I added Parallel Computing Toolbox and now it works. However, I can't see any difference in terms of speed, maybe for the processor itself.

[Rik]

Not every task can be sped up by throwing more cores at the problem.

If you want help with your specific task, you will have to post details about your specific task.