Editing Rainflow-counting algorithm (section)

=== Four point method ===
[[File:Rainflow-4point-method.png|thumb|Rainflow counting using the four point method. Any pair of turning points B,C that lie between adjacent points A and D is a rainflow cycle. Count and eliminate the pair B,C and continue processing the sequence until no more cycles can be extracted.]]
This method evaluates each set of 4 adjacent turning points A-B-C-D in turn:<ref name="lee12">{{cite book |title=Metal Fatigue Analysis Handbook|chapter=Rainflow Cycle Counting Techniques |first1=Yung-Li |last1=Lee |first2=Tana |last2=Tjhung  |year=2012 |pages=89–114 |doi=10.1016/B978-0-12-385204-5.00003-3|isbn=9780123852045 }}</ref>

# Any pair of points B-C that lies within or equal to A-D is a rainflow cycle.
# Remove the pair B-C and re-evaluate the sequence from the beginning.
# Continue until no further pairs can be identified.