What is Z-transform and inverse Z-transform?
Z-Transform is basically a discrete time counterpart of Laplace Transform. Z-transform of a general discrete time signal is expressed in the equation-1 above. The range of values of 'Z' for which above equation is defined gives ROC (Reason of Convergence) of Z-transform.
What is residue theorem formula?
From the residue theorem (which produces a factor 2πi that cancels the similar factor in the definition of J), we getf(t)=J=(residue atz=a+ik)+(residue atz=a-ik).