discrete H-infinity norm
hinfnorm=dhnorm(sl,[tol],[normax])
the state space system (syslin list) (discrete-time)
tolerance in bisection step, default value 0.01
upper bound for the norm , default value is 1000
the discrete infinity norm of Sl
produces the discrete-time infinity norm of a state-space system (the maximum over all frequencies on the unit circle of the maximum singular value).