Constant functions

Provides the value of various constants, according to the contents of string g: e (for a string of 'e' or 'E'), π ('pi' or 'PI'), missing value ('*'), conversion factor for obtaining degrees from radians ('degrees'), conversion factor for obtaining radians from degrees ('radians') and the number ε defined as the smallest number such that the calculation 1+ε is detectable on the computer as greater than one ('epsilon'). (Synonym C(g).)