# WaveTrend Oscillator

`D07-F03-A23` · Technical Indicators → Momentum · archetype `series-transform` · difficulty 2/5 · verification **verified**

Full page: https://docs.thefintechbuilder.com/technical-indicators/momentum/wavetrend-oscillator/
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 { wavetrendOscillator } from "fintech-algorithms/technical-indicators/momentum/wavetrend-oscillator";
```

## Signature

```ts
wavetrendOscillator(input)
```

Builds a CCI-style channel index from the typical price against its own 10-period EMA and mean deviation, then smooths it into a fast line and a slower trigger.

## Parameters

| Name | Type | Required | Notes |
| --- | --- | --- | --- |
| `input` | `TopicInput` | yes | `bars` is a chronological array of OHLCV rows, each with a non-empty `timestamp` plus finite `open`, `high`, `low`, `close` and `volume`. This topic reads no keys from `parameters`: the typical price is `(high + low + close) / 3` and the 10, 10, 21 and 4 lengths are fixed in the implementation. The shared momentum preamble still validates `period` (default 14), `fast_period` (default 5) and `slow_period` (default 34) before branching, so a bad value for any of them throws even though this topic reads none of them. |

## Returns

`TopicResult`

`series` and `latest` carry two keys: `wt1`, the 21-period EMA of the channel index, and `wt2`, the 4-period simple average of `wt1`. The two keys have different warm-ups, `wt2` trailing `wt1` by three bars.

## Warm-up

The first `38 bars for `wt1`, 41 bars for `wt2`` positions are `null`. The 10-period EMA of typical price seeds at index 9, its mean-deviation EMA at 18, and the 21-period EMA at 38, so `ready_at` is 38 on the canonical fixture; `wt2` remains null until index 41. A mean deviation of exactly 0 also yields a null.

## Errors

- When `period` is supplied but is not an integer >= 2, even though this topic ignores it — throws Error
- When a bar's `high` is below its `open`, `close`, or `low` — 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
wavetrendOscillator(input)
```

### Returns

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

```json
{
  "topic_id": "D07-F03-A23",
  "title": "WaveTrend Oscillator",
  "state": "calculated",
  "ready": true,
  "ready_at": 38,
  "series": {
    "wt1": [null, null, null, null, null, null],
    "wt2": [null, null, null, null, null, null]
  },
  "latest": {
    "wt1": -25.94276818159519,
    "wt2": -13.858032304032271
  },
  "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/technical-indicators/momentum/wavetrend-oscillator/
- Implementation source: https://github.com/IslamBaraka90/Fintech-Algorithms-Library/blob/main/src/technical-indicators/momentum/wavetrend-oscillator/impl.ts
- Package on npm: https://www.npmjs.com/package/fintech-algorithms
- Domain index for agents: https://docs.thefintechbuilder.com/technical-indicators/llms.txt