Force Index

Install and import

bash

npm install fintech-algorithms

import { force_index } from "fintech-algorithms/technical-indicators/volume-indicators/force-index";

Signature

force_index(close, volume, p)

Price change multiplied by volume, then smoothed. Combines direction, size and participation in one number — a large move on no volume scores low.

Parameters

Name	Type	Notes
`close`	`number[]`	Per-bar closing prices, chronological.
`volume`	`number[]`	Per-bar traded volume, aligned index-for-index with the price series.
`p`	`number`	EMA span applied to the raw force series. min: 1 · integer: true

Returns

Record<string, (number | null)[]> · length same-as-input

Parallel series: change, volume, raw_force, ema_seed and the smoothed force_index.

Warm-up

The first p positions are null. One bar for the price change, then the EMA seed window.

Errors

When p < 1 or is not an integer — throws RangeError
When the input series are not all the same length — throws RangeError

Complexity: time O(n), space O(n).

Worked example

executed 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

[100.28, 100.686113, 101.200346, 101.789282, 102.408843, 103.010585]

Showing 6 of 120 elements.

volume

[990000, 1066468.036, 1130033.236, 1170141.961, 1180511.26, 1160272.794]

Showing 6 of 120 elements.

Call

force_index(close, volume, p)

Returns

object with 5 fields: change, volume, raw_force, ema_seed, force_index

{
  "change": [
    null,
    0.40611300000000483,
    0.5142329999999902,
    0.5889360000000039,
    0.6195610000000045,
    0.6017420000000016
  ],
  "volume": [990000, 1066468.036, 1130033.236, 1170141.961, 1180511.26, 1160272.794],
  "raw_force": [
    null,
    433106.53350407316,
    581100.3810479769,
    689138.7259435005,
    731398.7367568653,
    698184.8716071498
  ],
  "ema_seed": [null, null, null, null, null, null],
  "force_index": [null, null, null, null, null, null]
}

Other exports

This module also exports obv, accumulation_distribution_line, chaikin_money_flow, money_flow_index, volume_price_trend. Every module additionally exports run as an alias of its primary function, and a meta object carrying its catalog id, domain, family, shape and article URL.

Diagrams

How it works

This page states the contract — how to call it correctly. The article explains the concept: why it works, and where it breaks.

Read the article →

References

Elder's Force Index (EFI) — TradingView
Volume — TradingView
Consolidated Tape — U.S. Securities and Exchange Commission, Investor.gov
Closing Price — U.S. Securities and Exchange Commission, Investor.gov
What is Volume? — CME Group
Claim-role ledger
Evidence boundary
Enhanced claim-to-source map
Public evidence boundary