# 3.5.2.30 Movrms

## Description

The function returns a vector to calculate the root mean square(rms) of adjacent ranges [i-nb, i+nf], for a point i

The root mean square of adjacent ranges at point i is given by

$x_{\mathrm{rms}}=\sqrt{ \frac{ \sum_{i-nb}^{i+nf} x_i^2 }{nb+nf+1} }$

where $nb$ is the backward offset and $nf$ is the forward offset

## Syntax

vector Movrms(vector vx, int back[, int forward])

## Parameters

vx

Input data vector used to calculate adjacent rms.

back

Input integer for the offset backward with respect to current row number.

forward

Input integer for the offset forward with respect to current row number. If forward is omitted, it will be set to be equal to back internally

## Return

Notes: The boundary will be treated with the way below

$y_i=\left\{\begin{matrix} RMS([x_0, x_{i+forward}]), & \textup{if} \; i <= back -1;\\ RMS([x_{i-back}, x_{n-1}]), & \textup{if} \; i > n-1-forward. \end{matrix}\right.$

## Example

//Col(B) will be filled with rms at each point for data within the window [i-2, i+2]
//Col(C) will be filled with rms at each point for data within the window [i, i+2]
for(ii=1;ii<=30;ii++) col(A)[ii] = ii;
col(B)=movrms(col(1),2);
col(C)=movrms(col(1),0, 2);