# Rolling Support and Resistance

`D08-F01-A10` · 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/rolling-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 { rollingSupportAndResistance } from "fintech-algorithms/geometric-chart-patterns/pivots-and-levels/rolling-support-and-resistance";
```

## Signature

```ts
rollingSupportAndResistance(input)
```

Reports, for each bar, the lowest low and highest high of the `period` bars that came strictly before it. Excluding the current bar is what makes the level a thing price can break rather than a level price defines.

## 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 lookback window. |

## Returns

`TopicResult`

`series` and `latest` carry `support` (rolling minimum low) and `resistance` (rolling maximum high). The warm-up is `period` bars, so with the default `ready_at` is 20.

## Warm-up

The first `period bars (20 by default)` positions are `null`. The window looks back over indices i-period through i-1, so index period is the first bar with a full prior window and `ready_at` equals `period`.

## Errors

- When `period` is supplied as a non-integer or as a value below 2 — throws Error
- When bars are not strictly increasing by `timestamp` — 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
rollingSupportAndResistance(input)
```

### Returns

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

```json
{
  "topic_id": "D08-F01-A10",
  "title": "Rolling Support and Resistance",
  "state": "calculated",
  "ready": true,
  "ready_at": 20,
  "series": {
    "support": [null, null, null, null, null, null],
    "resistance": [null, null, null, null, null, null]
  },
  "latest": {
    "support": 99.69159419,
    "resistance": 109.83623682
  },
  "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/rolling-support-and-resistance/
- Implementation source: https://github.com/IslamBaraka90/Fintech-Algorithms-Library/blob/main/src/geometric-chart-patterns/pivots-and-levels/rolling-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