# True Strength Index (TSI)

Created by William Blau, the True Strength Index is a momentum oscillator that uses a series of exponential moving averages to depicts trends in price changes. [Discuss]

```
// usage
IEnumerable<TsiResult> results =
quotes.GetTsi(lookbackPeriods, smoothPeriods, signalPeriods);
```

## Parameters

`lookbackPeriods`

* int* - Number of periods (

`N`

) for the first EMA. Must be greater than 0. Default is 25.`smoothPeriods`

* int* - Number of periods (

`M`

) for the second smoothing. Must be greater than 0. Default is 13.`signalPeriods`

* int* - Number of periods (

`S`

) in the TSI moving average. Must be greater than or equal to 0. Default is 7.### Historical quotes requirements

You must have at least `N+M+100`

periods of `quotes`

to cover the convergence periods. Since this uses a two EMA smoothing techniques, we recommend you use at least `N+M+250`

data points prior to the intended usage date for better precision.

`quotes`

is a collection of generic `TQuote`

historical price quotes. It should have a consistent frequency (day, hour, minute, etc). See the Guide for more information.

## Response

```
IEnumerable<TsiResult>
```

- This method returns a time series of all available indicator values for the
`quotes`

provided. - It always returns the same number of elements as there are in the historical quotes.
- It does not return a single incremental indicator value.
- The first
`N+M-1`

periods will have`null`

values since there’s not enough data to calculate. -
`Signal`

will be`null`

for all periods if`signalPeriods=0`

.

Convergence warning: The first`N+M+250`

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

### TsiResult

`Date`

* DateTime* - Date from evaluated

`TQuote`

`Tsi`

* double* - True Strength Index

`Signal`

* double* - Signal line (EMA of TSI)

### Utilities

See Utilities and helpers for more information.

## Chaining

This indicator may be generated from any chain-enabled indicator or method.

```
// example
var results = quotes
.Use(CandlePart.HL2)
.GetTsi(..);
```

Results can be further processed on `Tsi`

with additional chain-enabled indicators.

```
// example
var results = quotes
.GetTsi(..)
.GetSlope(..);
```