# Relative strength index

`rsi`

Momentum bounded 0 to 100, from average gains against average losses.

## Inputs

| Name | Type | Default | Range |
| --- | --- | --- | --- |
| source | source | close |  |
| period | int | 14 | 1 to 5000 |
| method | choice | wilder |  |

## Outputs

| Name | Kind |
| --- | --- |
| rsi | value |

Warm-up: period bars (14 at the defaults).

Repaints: No.

## Formula

gain = the change when it is positive, loss = minus the change when it is negative

wilder: the averages start as the mean of the first period gains and losses, then average = (previous average * (period - 1) + value) / period

cutler: the averages are simple means of the last period gains and losses

RSI = 100 * AvgGain / (AvgGain + AvgLoss)

A window with no gain and no loss reads 50.