Signal Toolkit - zplane

Function File: zplane (z, p)

Function File: zplane (b, a)

Plot the poles and zeros on a complex plane. If the arguments are column vectors z and p, the complex zeros z and poles p are displayed. If the arguments are row vectors b and a, the zeros and poles of the transfer function represented by these filter coefficients are displayed.

If z and p are matrices, the columns are distinct sets of zeros and poles and are displayed together in distinct colors.

Note that due to the nature of the roots function, poles and zeros may be displayed as occurring around a circle rather than at a single point.

The transfer function is

        B(z)   b0 + b1 z^(-1) + b2 z^(-2) + ... + bM z^(-M)
 H(z) = ---- = --------------------------------------------
        A(z)   a0 + a1 z^(-1) + a2 z^(-2) + ... + aN z^(-N)

               b0          (z - z1) (z - z2) ... (z - zM)
             = -- z^(-M+N) ------------------------------
               a0          (z - p1) (z - p2) ... (z - pN)
 

If called with only one argument, the poles p defaults to an empty vector, and the denominator coefficient vector a defaults to 1.