# Source code for deltasigma._rms

# -*- coding: utf-8 -*-
# _rms.py
# This module provides the rms function.
# 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
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# LICENSE file for the licensing terms.

"""This module provides the rms() function, which calculates the Root Mean
Square (RMS) of a vector.
"""

import numpy as np
import numpy.linalg as la

[docs]def rms(x, no_dc=False):
"""Calculate the RMS value of x.

The Root Mean Square value of an array :math:x of length :math:n is defined as:

.. math::

x_{RMS} = \\sqrt{\\frac{1}{n}(x_1^2 + x_2^2 + ...+x_n^2)}

**Parameters:**

x : (N,) ndarray
The input vector

no_dc : boolean, optional
If set to True, the DC value gets subtracted from x first and the RMS is computed on the result.

**Returns:**

xrms : scalar
as defined above

"""
if no_dc:
x = x - np.mean(x)
return la.norm(x)/np.sqrt(max(x.shape))