Source code for deltasigma._l1norm

# -*- coding: utf-8 -*-
# Module providing the l1norm function
# Copyright 2013 Giuseppe Venturini
# This file is part of python-deltasigma.
# python-deltasigma is a 1:1 Python replacement of Richard Schreier's
# MATLAB delta sigma toolbox (aka "delsigma"), upon which it is heavily based.
# The delta sigma toolbox is (c) 2009, Richard Schreier.
# python-deltasigma is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# LICENSE file for the licensing terms.

"""Module providing the l1norm() function

from __future__ import division

from warnings import warn

import numpy as np
from scipy.signal import dimpulse, lti

from ._utils import _get_zpk, _is_A_B_C_D, _is_num_den, _is_zpk

[docs]def l1norm(H): """Compute the l1-norm of a z-domain transfer function. The norm is evaluated over the first 100 samples. **Parameters:** H : sequence or lti object Any supported LTI representation is accepted. **Returns:** l1normH : float The L1 norm of ``H``. .. note: LTI objects are translated to ZPK tuples, with possible rounding errors. """ if _is_zpk(H): z, p, k = H HP = (z, p, k, 1.) elif _is_num_den(H): num, den = H HP = (num, den, 1.) elif _is_A_B_C_D(H): A, B, C, D = H HP = (A, B, C, D, 1.) elif isinstance(H, lti): warn('l1norm() got an LTI object, translated to zpk form, rounding errors possible.') z, p, k = _get_zpk(H) HP = (z, p, k, 1.) _, y = dimpulse(HP, t=np.arange(100)) return np.sum(np.abs(y[0]))