# Volatility Regime Classifier

`D08-F07-A13` · Geometric Chart Patterns → Market Structure, Breakouts, and Regimes · archetype `record-transform` · difficulty 2/5 · verification **verified**

Full page: https://docs.thefintechbuilder.com/geometric-chart-patterns/market-structure-breakouts-and-regimes/volatility-regime-classifier/
Agent skill: `npx skills add IslamBaraka90/Fintech-Algorithms-Library` — https://docs.thefintechbuilder.com/guides/agent-skill/

## Install and import

```bash
npm install fintech-algorithms
```

```ts
import { volatilityRegimeClassifier } from "fintech-algorithms/geometric-chart-patterns/market-structure-breakouts-and-regimes/volatility-regime-classifier";
```

## Signature

```ts
volatilityRegimeClassifier(input)
```

Computes realized volatility as the standard deviation of simple close returns over `period` bars, then ranks each reading against the last `rank_period` of them: bottom quartile is `low`, top quartile is `high`, everything between is `normal`.

## Parameters

| Name | Type | Required | Notes |
| --- | --- | --- | --- |
| `input` | `TopicInput` | yes | `bars` is the required OHLCV history, strictly ordered by `timestamp` and on a single adjustment basis. `parameters.period` (default `20`, integer of at least 2) sets the volatility window; `parameters.rank_period` (default `40`) sets the ranking history and must be an integer of at least `period`. |

## Returns

`TopicResult`

`series` and `latest` carry `volatility` and the string series `regime`. The warm-up is uneven: `volatility` needs `period` bars, so `ready_at` is 20 with the defaults, but `regime` needs a full `rank_period` of non-null volatilities behind it and so first appears at index `period + rank_period - 1`, which is 59 by default.

## Warm-up

The first `period bars for volatility, period + rank_period - 1 for regime` positions are `null`. The return series is null at index 0, so the standard deviation window first completes at index `period`. The rank window then needs `rank_period` consecutive non-null volatilities, pushing the first label much later than `ready_at` suggests.

## Errors

- When `rank_period` is supplied as a non-integer or as a value below `period` — throws Error
- When `period` is supplied as a non-integer or as a value below 2 — throws Error

## Complexity

Time `O(n × (period + rank_period))`, space `O(n)`.

## Worked example

Captured by running this function on the input its own test provides. Real output of real code — but not asserted against a published figure.

### Input

`input`:

```json
{
  "bars": [
    {
      "timestamp": "2024-01-02",
      "basis": "synthetic-unadjusted",
      "open": 100,
      "high": 101.45,
      "low": 98.695,
      "close": 100,
      "volume": 750000,
      "benchmark": 200
    },
    {
      "timestamp": "2024-01-03",
      "basis": "synthetic-unadjusted",
      "open": 101.49111452,
      "high": 103.38381693,
      "low": 100.05480022,
      "close": 101.78791214,
      "volume": 795117,
      "benchmark": 200.56326135
    },
    {
      "timestamp": "2024-01-04",
      "basis": "synthetic-unadjusted",
      "open": 102.45519048,
      "high": 104.6701838,
      "low": 100.91147007,
      "close": 102.9549389,
      "volume": 840234,
      "benchmark": 201.11020913
    }
  ],
  "parameters": {}
}
```

### Call

```ts
volatilityRegimeClassifier(input)
```

### Returns

object with 9 fields: topic_id, title, state, ready, ready_at, series, latest, parameters, …

```json
{
  "topic_id": "D08-F07-A13",
  "title": "Volatility Regime Classifier",
  "state": "calculated",
  "ready": true,
  "ready_at": 20,
  "series": {
    "volatility": [null, null, null, null, null, null],
    "regime": [null, null, null, null, null, null]
  },
  "latest": {
    "volatility": 0.008703709337001016,
    "regime": "normal"
  },
  "parameters": {},
  "diagnostics": {
    "causal": true,
    "input_count": 96
  }
}
```

## Verification and provenance

Tier: **verified** (via E).

The worked example below is the figure published in this algorithm's article, replayed and asserted by the test suite on every build. The arithmetic cannot drift without the build failing.

Both tiers guarantee the signature. Full explanation: https://docs.thefintechbuilder.com/guides/verification/

Generated from the docs.json payload shipped inside fintech-algorithms@0.13.0.
The signature and parameter list are checked against the compiled implementation at build time,
so a description that contradicts the code fails the build rather than reaching this file.

## Links

- Article (how it works, step by step): https://thefintechbuilder.com/geometric-chart-patterns/market-structure-breakouts-and-regimes/volatility-regime-classifier/
- Implementation source: https://github.com/IslamBaraka90/Fintech-Algorithms-Library/blob/main/src/geometric-chart-patterns/market-structure-breakouts-and-regimes/volatility-regime-classifier/impl.ts
- Package on npm: https://www.npmjs.com/package/fintech-algorithms
- Domain index for agents: https://docs.thefintechbuilder.com/geometric-chart-patterns/llms.txt