Variables

A variable is a sequence of letters, digits and underscores, the first of which must
be a letter. CalcSharp supports user-defined variables and has predefined frequently
used constants from mathematics, physics and informatics.

Examples:
MYVAR, myvar44, MY_var, A1, Q_123, PI__

More comprehensive list of mathematical constants ( thanks to Anthony Felder and
Steven Finch ) can be found here. Complete list of fundamental physical constants
can be found here.