The Aroon indicator measures the temporal freshness of price extremes. Unlike oscillators that obsess over *how much* price has moved, Aroon asks *how long* it has been since a new high or low. It quantifies the "staleness" of a trend, providing an early warning system for consolidation and reversals.
Tushar Chande introduced Aroon in *Beyond Technical Analysis* (1995). The name comes from the Sanskrit word for "Dawn's Early Light." Chande's insight was that trends don't just stop; they age. By measuring the time elapsed since the last extreme, Aroon attempts to spot the "dawn" of a new trend rather than just confirming an existing one.
The implementation uses a circular buffer (`RingBuffer`) to store historical highs and lows, ensuring O(1) access and zero heap allocations during the update cycle. The min/max search is performed in-place on the buffer.
| Metric | Score | Notes |
| :--- | :--- | :--- |
| **Throughput** | 10ns | 10ns / bar. |
| **Allocations** | 0 | Hot path is allocation-free. |
| **Complexity** | O(P) | Linear scan for extremes. |
| **Accuracy** | 10/10 | Matches standard implementations. |
| **Timeliness** | 10/10 | Reacts immediately to new extremes. |
- **Single Value Updates**: If you feed Aroon only `Close` prices (instead of High/Low), it degrades into a "Time Since Highest Close" metric. It works, but it loses the nuance of intraday extremes.
- **The 70/30 Rule**: A common interpretation is that a trend is strong only if the primary line is > 70. Values between 30 and 70 often indicate noise or consolidation.
