Pine Script offers a range of built-in functions that simplify the process of creating complex calculations. One such function is `ta.dev()`

, which measures the deviation of a data series from its simple moving average (SMA) over a specified period. This article will delve into the `ta.dev()`

function, explaining its syntax, arguments, and providing a practical example.

### Syntax of `ta.dev()`

The `ta.dev()`

function in Pine Script is used to calculate the average deviation of a series from its simple moving average (SMA). Its syntax is as follows:

ta.dev(source, length) → series float

#### Arguments

`source`

(series int/float): This is the series of values that`ta.dev()`

will process. It can be any series of prices or indicators.`length`

(series int): This specifies the number of bars to consider for the calculation. It determines the length of the SMA and the range over which the deviation is computed.

### Example

Below is an example of how to use the `ta.dev()`

function in Pine Script to plot the deviation of the close price from its 10-bar SMA.

//@version=5 indicator("ta.dev example") plot(ta.dev(close, 10))

### Custom Implementation:

For a deeper understanding of what `ta.dev()`

does under the hood, let’s examine a custom implementation named `pine_dev`

.

pine_dev(source, length) => mean = ta.sma(source, length) sum = 0.0 for i = 0 to length - 1 val = source[i] sum := sum + math.abs(val - mean) dev = sum / length plot(pine_dev(close, 10))

### Walkthrough

**Calculating the Mean**: First, we calculate the simple moving average (SMA) of the`source`

series over the specified`length`

using`ta.sma(source, length)`

. This serves as our mean around which we measure deviation.**Summing Deviations**: We initialize a variable`sum`

to zero. Then, using a for loop, we iterate over each bar in the specified`length`

range, calculating the absolute difference between the`source`

value at each bar and the mean. These differences are accumulated in`sum`

.**Calculating Average Deviation**: Finally, the sum of deviations is divided by the`length`

to find the average deviation, which is stored in`dev`

.

### Key Features and Takeaways

- The
`ta.dev()`

function is a built-in Pine Script function for measuring the average deviation of a series from its simple moving average over a specified period. - This function can be used to gauge the consistency of price movements or the variability of an indicator from its average.
- A custom implementation, like
`pine_dev`

, demonstrates the underlying calculation, reinforcing the concept of averaging deviations for a given length. - Understanding both the built-in
`ta.dev()`

and the custom`pine_dev`

function can enhance your Pine Script programming skills, especially in creating indicators that measure volatility or consistency in data series.

By exploring both the built-in `ta.dev()`

function and a custom implementation, you gain insights into the versatility of Pine Script for financial analysis and indicator development.