A tandem cosine algorithm for modeling rhythmic change

A tandem cosine algorithm which connects two or more successive half-waves is described, and may be used to represent many rhythmic ecological patterns, including air temperature patterns, vital signs such as body temperature rhythms, solar radiation patterns, and weight changes of mammals and birds over the annual cycle. Each of these is illustrated with an example in this paper. The tandem cosine algorithm is a pattern-generating procedure rather than a curve-fitting one, and may be used when few data are available. When modeling ecological relationships, it is better to represent rhythmic changes with a pattern than to ignore the rhythmic pattern and represent them with simple average values over time.