def np_vec_to_cut_vec(np_vec, decimals=4):
    """Converts a 3x1 numpy array to its representation in the CUT domain.
	
	:param np_vec: numpy array or None
	:param decimals: number of decimal places to round each element 
	in np_vec to. - integer - default = 4
	
	:return: Empty string if np_vec is None or len(np_vec) != 3. Otherwise, 
	the string '< x1, x2, x3 >' where x1, x2, x3 are the elements of np_vec
	rounded to decimals decimal places.
	"""
    if np_vec is None or len(np_vec) != 3:
        return ''
    else:
        return '< %.*f, %.*f, %.*f >' % (decimals, np_vec[0] + 0, decimals,
            np_vec[1] + 0, decimals, np_vec[2] + 0)
