MATLAB Zero Command
From ControlTheoryPro.com

1 Introduction to MATLAB's zero' command
The zero command computes the zeros of an LTI model whether that model is SISO or MIMO.
2 Usage
The zero command is a simple one.
>> z = zero(sys);
This will return the zeros of the LTI model sys. It doesn't matter if sys is a State Space object, Transfer Function, ZeroPoleGain model, or FRD (typically used fo rmeasured data).
Also, if you wish to use the zero command to recreat the system using the zpk command then zero will also return the system gain for SISO systems.
>> [z, gain] = zero(sys);
3 Notes
 This function requires the Control System Toolbox.