# Balance of Power

`D07-F03-A27` · Technical Indicators → Momentum · archetype `series-transform` · difficulty 2/5 · verification **verified**

Full page: https://docs.thefintechbuilder.com/technical-indicators/momentum/balance-of-power/
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 { balanceOfPower } from "fintech-algorithms/technical-indicators/momentum/balance-of-power";
```

## Signature

```ts
balanceOfPower(input)
```

Divides each candle's body by its full range, giving a per-bar -1..1 reading of how much of the session's travel the close managed to keep.

## 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 calculation is a single-bar ratio with no lookback. 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 one key, `value`, equal to `(close - open) / (high - low)` for each bar. There is no warm-up prefix, so the first bar already carries a reading.

## Warm-up

The first `none` positions are `a value at the first bar`. Every bar is self-contained, so `ready_at` is 0 on the canonical fixture. The one exception is a bar whose `high` equals its `low`, which has no range to divide by and yields a null at that index only.

## Errors

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

### Returns

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

```json
{
  "topic_id": "D07-F03-A27",
  "title": "Balance of Power",
  "state": "calculated",
  "ready": true,
  "ready_at": 0,
  "series": {
    "value": [
      0,
      0.08915474022958794,
      0.13295729760191172,
      0.13829149989844472,
      0.1089777590581788,
      0.04557026577834851
    ]
  },
  "latest": {
    "value": -0.11921211954649767
  },
  "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/balance-of-power/
- Implementation source: https://github.com/IslamBaraka90/Fintech-Algorithms-Library/blob/main/src/technical-indicators/momentum/balance-of-power/impl.ts
- Package on npm: https://www.npmjs.com/package/fintech-algorithms
- Domain index for agents: https://docs.thefintechbuilder.com/technical-indicators/llms.txt