---
title: HT_TRENDLINE
description: "Ehlers' Hilbert Transform Instantaneous Trendline: a smoothed, low-lag overlay whose averaging window adapts to the dominant cycle period measured via Hilbert-transform quadrature (I/Q) analysis of price."
---

# HT_TRENDLINE

## Summary

Ehlers' Hilbert Transform Instantaneous Trendline: a smoothed, low-lag overlay whose averaging window adapts to the dominant cycle period measured via Hilbert-transform quadrature (I/Q) analysis of price.

## Inputs

- `inReal` — Source price series

## Outputs

- `outReal` — Instantaneous trendline value

## Implementation

TA-Lib Definition: [`ht_trendline.c`](https://github.com/TA-Lib/ta-lib/blob/main/ta_codegen/input/ht_trendline/ht_trendline.c) · [`ht_trendline.yaml`](https://github.com/TA-Lib/ta-lib/blob/main/ta_codegen/input/ht_trendline/ht_trendline.yaml)

| Native | File |
|--------|------|
| C | [`ta_HT_TRENDLINE.c`](https://github.com/TA-Lib/ta-lib/blob/main/src/ta_func/ta_HT_TRENDLINE.c) |
| Rust | [`ht_trendline.rs`](https://github.com/TA-Lib/ta-lib/blob/main/ta_codegen/output/rust/src/ta_func/ht_trendline.rs) |
| Java | [`Core.java`](https://github.com/TA-Lib/ta-lib/blob/main/java/src/com/tictactec/ta/lib/Core.java) |

TA-Lib is also available for Python, R and more using a [wrapper](https://ta-lib.org/wrappers/).

## Aliases

Hilbert Transform Instantaneous Trendline, Instantaneous Trendline

## See Also

[HT_DCPERIOD](ht_dcperiod.md) · [HT_PHASOR](ht_phasor.md) · [MAMA](mama.md) · [WMA](wma.md)

## References

- John F. Ehlers, *Rocket Science for Traders: Digital Signal Processing Applications*, John Wiley & Sons (ISBN 0471405671)
