# ACOS

## Summary

Vector trigonometric arc cosine: applies acos() to each input value. A Math Transform passthrough with zero lookback.

## Formula

outReal[i] = acos(inReal[i])

## Inputs

- `inReal` — input values (expected in [-1, 1])

## Outputs

- `outReal` — arc cosine of each input, in radians

## Implementation

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

| Native | File |
|--------|------|
| C | [`ta_ACOS.c`](https://github.com/TA-Lib/ta-lib/blob/main/src/ta_func/ta_ACOS.c) |
| Rust | [`acos.rs`](https://github.com/TA-Lib/ta-lib/blob/main/ta_codegen/output/rust/src/ta_func/acos.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

Arc Cosine, Inverse Cosine, arccos

## See Also

COS · ASIN · ATAN
