def plzz(self, rotvel="", deltarotvel="", **kwargs):
    """Plots the interference diagram from a cyclic modal analysis.

    APDL Command: PLZZ

    Parameters
    ----------
    rotvel
        Rotational speed in revolutions per minute (RPM) used to define the
        speed line. If blank, use the rotational speed (from OMEGA)
        specified in the prestressing step of the linear perturbation
        analysis. If explicitly input as 0, or if the linear perturbation
        was not used, no speed lines are plotted.

    deltarotvel
        Adds speed lines about the RotVel speed line corresponding to
        RotVel ± DeltaRotVel. Only plotted if RotVel is known.

    Notes
    -----
    PLZZ plots the cyclic modal frequencies as points on a frequency vs.
    harmonic index (nodal diameter) graph. If rotational speed (RotVel) is
    provided, the speed line is also plotted, leading to the interference
    diagram (also known as the SAFE or ZZENF diagram). If DeltaRotVel is
    also provided, two additional speed lines are plotted, enveloping the
    safe speed line itself.

    For more information, see Postprocessing a Modal Cyclic Symmetry
    Analysis in the Cyclic Symmetry Analysis Guide.
    """
    command = f"PLZZ,{rotvel},{deltarotvel}"
    return self.run(command, **kwargs)