Emetophobia in which the phobic person will go to great lengths to avoid even potential situations that could even be perceived as "threatening". Emetophobia is clinically considered an "elusive predicament" because limited research has been done pertaining to it. The fear of vomiting receives little attention compared with other irrational fears. Frank M. Dattilio. "Emetic Exposure and Desensitization Procedures in the Reduction of Nausea and a Fear of Emesis." "Clinical Case Studies" 2.3 (2003): 199-210.</ref> The event of vomiting may make anyone with this peculiar phobia flee the scene. Some may fear someone throwing up, while others may fear themselves throwing
Periodic function were irrational, then the wave would not be periodic. Periodic function In mathematics, a periodic function is a function that repeats its values in regular intervals or periods. The most important examples are the trigonometric functions, which repeat over intervals of 2"π" radians. Periodic functions are used throughout science to describe oscillations, waves, and other phenomena that exhibit periodicity. Any function that is not periodic is called aperiodic. A function is said to be periodic if, for some nonzero constant , we have for all values of in the domain. A nonzero constant for which this is the case is