# PBands

##### Construct (optionally further smoothed and centered ) volatility bands around prices

John Bollinger's famous adaptive volatility bands most often use the typical
price of an HLC series, or may be calculated on a univariate price series
(see `BBands`

).

- Keywords
- ts

##### Usage

```
PBands(prices, n = 20, maType = "SMA", sd = 2, ..., fastn = 2,
centered = FALSE, lavg = FALSE)
```

##### Arguments

- prices
A univariate series of prices.

- n
Number of periods to average over.

- maType
A function or a string naming the function to be called.

- sd
The number of standard deviations to use.

- fastn
Number of periods to use for smoothing higher-frequency 'noise'.

- centered
Whether to center the bands around a series adjusted for high frequency noise, default

`FALSE`

.- lavg
Whether to use a longer

`(n*2)`

smoothing period for centering, default`FALSE`

.- …
any other pass-thru parameters, usually for function named by

`maType`

.

##### Details

This function applies a second moving average denoted by `fastn`

to
filter out higher-frequency noise, making the bands somewhat more stable to
temporary fluctuations and spikes.

If `centered`

is `TRUE`

, the function also further smoothes and
centers the bands around a centerline adjusted to remove this higher
frequency noise. If `lavg`

is also `TRUE`

, the smoothing applied
for the middle band (but not the volatility bands) is doubled to further
smooth the price-response function.

If you have multiple different price series in `prices`

, and want to use
this function, call this functions using `lapply(prices,PBands,...)`

.

##### Value

A object of the same class as `prices`

or a matrix (if
`try.xts`

fails) containing the columns:

- dn
The lower price volatility Band.

- center
The smoothed centerline (see details).

- up
The upper price volatility Band.

##### See Also

##### Examples

`library(TTR)`

```
# NOT RUN {
data(ttrc)
pbands.close <- PBands( ttrc[,"Close"] )
# }
```

*Documentation reproduced from package TTR, version 0.23-1, License: GPL-2*