# Apply N (APPLYN)

> QuantNexus indicator page for APPLYN utility logic.

**Route**: `/quantnexus/indicators/applyn/`

## What It Does

APPLYN applies a function to the last `n` values in a series. It is a general-purpose helper for custom rolling transformations.

## Formula

APPLYN computes a rolling transformation using the selected function, such as sum, mean, max, min, or standard deviation.

## Parameters

- `period` - default `14`
- `func` - default `sum`

## C++23 API

```cpp
#include <nonabt/indicators/applyn.hpp>
auto applyn = std::make_unique<nonabt::APPLYN>(data(), 14, "sum");
```

## Common Usage

- Use APPLYN for rolling aggregation logic.
- Combine it with custom logic pipelines.
- Useful for compacting multiple bars into one derived value.

## Practical Pattern

APPLYN is a utility building block rather than a pure entry signal indicator.