# Matching Low

`D06-F03-A11` · Price Action and Candlesticks → Two-Candle Patterns · archetype `record-transform` · difficulty 2/5 · verification **verified**

Full page: https://docs.thefintechbuilder.com/price-action-and-candlesticks/two-candle-patterns/matching-low/
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 { matchingLow } from "fintech-algorithms/price-action-and-candlesticks/two-candle-patterns/matching-low";
```

## Signature

```ts
matchingLow(input)
```

Scans consecutive pairs of bars for two down candles whose closes land within a tick of each other, marking a repeated closing floor.

## Parameters

| Name | Type | Required | Notes |
| --- | --- | --- | --- |
| `input` | `TopicInput` | yes | `bars` is a chronologically ordered array of OHLCV rows; each needs a non-empty `timestamp` strictly greater than the previous row's and finite `open`, `high`, `low`, `close` and `volume`. The pattern family validates `tick_tolerance` (default 0.01, at least 0) and `doji_body_ratio` (default 0.05, within 0..1) on every call, but this topic reads only `tick_tolerance`, the largest gap between the two closes that still counts as a match. |

## Returns

`TopicResult`

`series.matched` is the boolean verdict for the pair ending at that index, and `series.label` is `"bullish"` when it fires and `"none"` when it does not; this topic emits no bearish label. `latest` carries the last value of each. The warm-up is the one leading bar that has no predecessor.

## Warm-up

The first `1 bar` positions are `null`. The pattern needs a two-bar window, so both series hold null at index 0 and `ready_at` is 1. From index 1 onward `matched` is false or true, and false is a real verdict rather than a warm-up placeholder, so `ready_at` does not depend on any pattern ever firing. A one-bar input returns null throughout, with `ready_at` null and `state` "waiting".

## Errors

- When a bar has a non-finite price or volume, a negative volume, a `high` below its own open/low/close, a `low` above them, or a `timestamp` that does not advance — throws Error
- When `tick_tolerance` is not a finite number or is negative, or `doji_body_ratio` falls outside 0..1 — throws Error
- When `input` is not an object, `input.parameters` is not an object, or `bars` is not an array holding at least one bar — throws Error

## Complexity

Time `O(n)`, 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
matchingLow(input)
```

### Returns

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

```json
{
  "topic_id": "D06-F03-A11",
  "title": "Matching Low",
  "state": "calculated",
  "ready": true,
  "ready_at": 1,
  "series": {
    "label": [null, "none", "none", "none", "none", "none"],
    "matched": [null, false, false, false, false, false]
  },
  "latest": {
    "label": "none",
    "matched": false
  },
  "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/price-action-and-candlesticks/two-candle-patterns/matching-low/
- Implementation source: https://github.com/IslamBaraka90/Fintech-Algorithms-Library/blob/main/src/price-action-and-candlesticks/two-candle-patterns/matching-low/impl.ts
- Package on npm: https://www.npmjs.com/package/fintech-algorithms
- Domain index for agents: https://docs.thefintechbuilder.com/price-action-and-candlesticks/llms.txt