Rainflow

Rainflow Counting Algorithm (4-point-method), C99 compliant.

"Rainflow Counting" consists of four main steps:
1. Hysteresis Filtering
2. Peak-Valley Filtering
3. Discretization
4. Four Point Counting Method:

These steps are fully documented in standards such as ASTM E1049 "Standard Practices for Cycle Counting in Fatigue Analysis" [1].
This implementation uses the 4-point algorithm mentioned in [2].
To take the residue into account, you may implement a custom method or use some predefined functions.

[1] ASTM Standard E 1049, 1985 (2011). "Standard Practices for Cycle Counting in Fatigue Analysis", West Conshohocken, PA: ASTM International, 2011.
[2] [https://community.plm.automation.siemens.com/t5/Testing-Knowledge-Base/Rainflow-Counting/ta-p/383093]