def set_minimum(min_freq=None, min_time=None, min_off=None, min_res=None,
    min_angle=None):
    """
    Set minimum values of parameters.

    The given parameters are set to its minimum value if they are smaller.

    .. note::

        set_minimum and get_minimum are derived after set_printoptions and
        get_printoptions from arrayprint.py in numpy.

    Parameters
    ----------
    min_freq : float, optional
        Minimum frequency [Hz] (default 1e-20 Hz).
    min_time : float, optional
        Minimum time [s] (default 1e-20 s).
    min_off : float, optional
        Minimum offset [m] (default 1e-3 m).
        Also used to round src- & rec-coordinates.
    min_res : float, optional
        Minimum horizontal and vertical resistivity [Ohm.m] (default 1e-20).
    min_angle : float, optional
        Minimum angle [-] (default 1e-10).

    """
    global _min_freq, _min_time, _min_off, _min_res, _min_angle
    if min_freq is not None:
        _min_freq = min_freq
    if min_time is not None:
        _min_time = min_time
    if min_off is not None:
        _min_off = min_off
    if min_res is not None:
        _min_res = min_res
    if min_angle is not None:
        _min_angle = min_angle
