# series_moving_avg_fl()

Applies a moving average filter on a series.

The function `series_moving_avg_fl()` is a user-defined function (UDF) that takes an expression containing a dynamic numerical array as input and applies on it a simple moving average filter.

## Syntax

`series_moving_avg_fl(`y_series`,` n [`,` center ]`)`

## Parameters

Name Type Required Description
y_series `dynamic` ✔️ An array cell of numeric values.
n `int` ✔️ The width of the moving average filter.
center `bool` Indicates whether the moving average is either applied symmetrically on a window before and after the current point or applied on a window from the current point backwards. By default, center is `false`.

## Function definition

You can define the function by either embedding its code as a query-defined function, or creating it as a stored function in your database, as follows:

Define the function using the following let statement. No permissions are required.

Important

A let statement can't run on its own. It must be followed by a tabular expression statement. To run a working example of `series_moving_avg_fl()`, see Example.

``````let series_moving_avg_fl = (y_series:dynamic, n:int, center:bool=false)
{
series_fir(y_series, repeat(1, n), true, center)
};
// Write your query to use the function here.
``````

## Example

The following example uses the invoke operator to run the function.

To use a query-defined function, invoke it after the embedded function definition.

``````let series_moving_avg_fl = (y_series:dynamic, n:int, center:bool=false)
{
series_fir(y_series, repeat(1, n), true, center)
};
//
//  Moving average of 5 bins
//
demo_make_series1
| make-series num=count() on TimeStamp step 1h by OsVer
| extend num_ma=series_moving_avg_fl(num, 5, True)
| render timechart
``````

Output