def update_minmax(dic, data):
    """
    Update the MAX/MIN dictionary keys.
    """
    # maximum and minimum values
    dic["FDMAX"] = float(data.max().real)
    dic["FDDISPMAX"] = dic["FDMAX"]
    dic["FDMIN"] = float(data.min().real)
    dic["FDDISPMIN"] = dic["FDMIN"]
    dic["FDSCALEFLAG"] = 1.0    # FDMIN/MAX are valid
    return dic