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
Positive-real function general definition, and then particularize it to the rational case. Linear electrical networks with more than one port may be described by impedance or admittance matrices. So by extending the definition of PR to matrix-valued functions, linear multi-port networks which are passive may be distinguished from those that are not. A possibly irrational matrix-valued function "Z"("s") is PR if and only if Positive-real function Positive-real functions, often abbreviated to PR function, are a kind of mathematical function that first arose in electrical network analysis. They are complex functions, "Z"("s"), of a complex variable, "s". A rational function is defined to