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Force Index

Created by Alexander Elder, the Force Index depicts volume-based buying and selling pressure based on the change in price. [Discuss] 💬

csharp
// C# usage syntax
IReadOnlyList<ForceIndexResult> results =
  bars.ToForceIndex(lookbackPeriods);

Parameters

paramtypedescription
lookbackPeriodsintLookback window (N) for the EMA of Force Index. Must be greater than 0 and is commonly 2 or 13 (shorter/longer view). Default is 2.

Historical price bars requirements

You must have at least N+100 for 2×N periods of bars, whichever is more, to cover the warmup and convergence periods. Since this uses a smoothing technique for EMA, we recommend you use at least N+250 data points prior to the intended usage date for better precision.

bars is a collection of generic TBar historical price bars. It should have a consistent frequency (day, hour, minute, etc). See the Guide for more information.

Response

csharp
IReadOnlyList<ForceIndexResult>
  • This method returns a time series of all available indicator values for the bars provided.
  • It always returns the same number of elements as there are in the historical price bars.
  • It does not return a single incremental indicator value.
  • The first N periods will be null since they cannot be calculated.

🚩 ⚞ Convergence warning

The first N+100 periods will have decreasing magnitude, convergence-related precision errors that can be as high as ~5% deviation in indicator values for earlier periods.

ForceIndexResult

propertytypedescription
TimestampDateTimeDate from evaluated TBar
ForceIndexdoubleForce Index

Utilities

See Utilities and helpers for more information.

Chaining

Results can be further processed on ForceIndex with additional chain-enabled indicators.

csharp
// example
var results = bars
    .ToForceIndex(..)
    .ToEma(..);

This indicator must be generated from bars and cannot be generated from results of another chain-enabled indicator or method.

See Chaining indicators for more.

Streaming

Use the buffer-style List<T> when you need incremental calculations without a hub:

csharp
ForceIndexList forceIndexList = new(lookbackPeriods);

foreach (IBar bar in bars)  // simulating stream
{
  forceIndexList.Add(bar);
}

// based on `ICollection<ForceIndexResult>`
IReadOnlyList<ForceIndexResult> results = forceIndexList;

Subscribe to a BarHub for advanced streaming scenarios:

csharp
BarHub barHub = new();
ForceIndexHub observer = barHub.ToForceIndexHub(lookbackPeriods);

foreach (IBar bar in bars)  // simulating stream
{
  barHub.Add(bar);
}

IReadOnlyList<ForceIndexResult> results = observer.Results;

See Buffer lists and Stream hubs for full usage guides.