operation problem after use 'qlogin' in linux system

Hi:

in the linux system, I log into a node and want to check the cores available for parallel computing, below is my code:

    module load matlab/R2018b
    matlab -nosplash -nodesktop
    system('qlogin')
    numcores = feature('numcores')

but Matlab reported error:

    Badly placed ()'s.

however, if I log into a node and run Matlab first, I'm able check number of cores:

    module load matlab/R2018b
    matlab -nosplash -nodesktop
    numcores = feature('numcores') 

so just want know, is there any mistake with my operation?

Thanks!

Yu