If your transform inovlves calcuations, then they will be performed using the
uCalc Fast Math Parser object set with this function, or a default math parser
object if this function is not called. Each math parser can have its own sets of
variables, functions, and other definitions.
If you pass the handle to an existing math parser, then that one will be used. If nothing is passed to
the function, then this function will merely return the existing math parser object.