How to specify number of threads a matlab session can use

I have read many other 'answers' on this matter, but I am not succeeding.

I have a heavily vectorized code that I want to run, but I want to limit the number of cores that a matlab session can use because I want to run the same code many times at once (using multiple simultaneously running matlab sessions). This should prevent any bottlenecking of cpu power which I expect to increase efficiency.

Anyways, I've tried:

 parpool(1)

and

 maxNumCompThreads=1

but both fail as task manager indicates that many cores continue to be used.

How do I do this?

[Adam]

parpool(1) works fine for me.

Answer 1

[Sean de Wolski]

Start MATLAB from the system command prompt with -singleCompThread flag.

Or use the Parallel Computing Toolbox and parfor or spmd to run on multiple MATLAB workers in Parallel.