def _nd4j_datatype_from_np(np_datatype_name):
    """

    :param np_datatype_name:
    a numpy data type name.
    1 of:
    float64
    float32
    float16
    :return: the equivalent nd4j data type name (double,float,half)
    """
    if np_datatype_name == 'float64':
        return 'double'
    elif np_datatype_name == 'float32':
        return 'float'
    elif np_datatype_name == 'float16':
        return 'half'
    return None