“Module 7– Z-Transform in MATLAB” • Work the below lab assignment below using MATLAB. • Include answers for Problems and include MATLAB coding along with any output plots that support solutions into a Word document 

Activity 1: A linear time-invariant discrete-time system has transfer function 

H(z)=(z^2-z-2)/(z^2+1.5z-1)

• Use Matlab to obtain the poles of the system. Is the system stable? Explain. 

• Matlab tip: You can find the roots of a polynomial by using the roots command. For instance, if you have the polynomial x2+ 4x + 3, then you can find the roots of this polynomial as follows: >>roots([1 4 3]) where the array is the coefficients of the polynomial. 

• Compute the step response. This should be done analytically, but you can use Matlab commands like conv and residue to help you in the calculations. 

• Matlab tip: Besides using conv to look at the response of a system, it can also be used to multiply two polynomials together. For instance, if you want to know the product (x2 + 4x + 3)(x + 1), you can do the following: >>conv([1 4 3],[1 1]) where the two arrays are the coefficients of the two polynomials. The result is >> ans = 1 5 7 3 Thus, the product of the two polynomials is x3 + 5×2 + 7x + 3. 

Matlab tip: The command residue does the partial fraction expansion of the ratio of two polynomials. In our case, we can obtain Y(z)/z and then use the residue command to do the partial fraction expansion. Then it is relatively easy to obtain y[n] using the tables.

• Plot the first seven values of the step response. Is the response increasing or decreasing with time? Is this what you would expect, and why?