Probably the oldest Biorhythm calculation app for smartphones (written in early 2002 for the Nokia 9210 Communicator) now ported to MeeGo Harmattan (Nokia N9 / N950), Symbian Anna/Belle, BlackBerry BB10 and Sailfish OS. Provides features missing from other apps of this kind: storing data of two persons and quickly switching between them, biorhythm interpretation, warning about critical days, scrollable graph, information about cycles (completed, day of current cycle, etc.) and more. Accurate and easy to use.
Its main screen is divided into three parts: buttons to select person, detailed biorhythm levels for the selected day (with some additional information like the number of completed cycles, day of current cycle, whether the biorhythm is currently rising or falling, etc.) and a scrollable graph.
Interpretation of the current biorhythm reading is available via the "Interpret" button. The program also contains a help page informing how to use the application, and a history and explanation of the biorhythm theory.
MeeGo Harmattan (Nokia N9 & N950) version: http://store.ovi.com/content/348910
Symbian Anna & Belle version: http://store.ovi.com/content/353043
BlackBerry BB10 version: http://appworld.blackberry.com/webstore/content/28025187/
Jolla (Sailfish OS) version is also ready for release.