# ATR Support and Resistance

`D08-F01-A12` · Geometric Chart Patterns → Pivots and Levels · archetype `record-transform` · difficulty 2/5 · verification **verified**

Full page: https://docs.thefintechbuilder.com/geometric-chart-patterns/pivots-and-levels/atr-support-and-resistance/
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 { atrSupportAndResistance } from "fintech-algorithms/geometric-chart-patterns/pivots-and-levels/atr-support-and-resistance";
```

## Signature

```ts
atrSupportAndResistance(input)
```

Places support and resistance a volatility-scaled distance either side of a simple moving average of close: `center ± multiplier × ATR(period)`, where the ATR is Wilder-smoothed true range.

## 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 both the moving average and the ATR length; `parameters.multiplier` (default `2`, finite and at least `0`) sets the band width. |

## Returns

`TopicResult`

`series` and `latest` carry `center`, `support` and `resistance`. The warm-up is `period - 1` bars, because the moving average and the ATR seed both complete at index `period - 1`, so with the default `ready_at` is 19.

## Warm-up

The first `period - 1 bars (19 by default)` positions are `null`. The simple moving average and the Wilder ATR seed both need `period` observations, and true range is defined from index 0, so all three series turn non-null together at index `period - 1`.

## Errors

- When `multiplier` is supplied as a negative number or is not finite — throws Error
- When `period` is supplied as a non-integer or as a value below 2 — throws Error

## Complexity

Time `O(n × 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
atrSupportAndResistance(input)
```

### Returns

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

```json
{
  "topic_id": "D08-F01-A12",
  "title": "ATR Support and Resistance",
  "state": "calculated",
  "ready": true,
  "ready_at": 19,
  "series": {
    "center": [null, null, null, null, null, null],
    "support": [null, null, null, null, null, null],
    "resistance": [null, null, null, null, null, null]
  },
  "latest": {
    "center": 104.20055051999998,
    "support": 97.75337766966595,
    "resistance": 110.647723370334
  },
  "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/pivots-and-levels/atr-support-and-resistance/
- Implementation source: https://github.com/IslamBaraka90/Fintech-Algorithms-Library/blob/main/src/geometric-chart-patterns/pivots-and-levels/atr-support-and-resistance/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