epoch Prime

[StephenG1CMZ]

Re Optional Parameters
The HP Prime does not have optional parameter as such (other than for built-in procedures).
The workarounds are:
1 To have the parameters in a list, which can vary in length and whose size can be checked.
2 To have the parameters always present.
3 Or to make the optional parameters globals.
Update (for completeness):
4 Eliminate the use of the optional parameter i.e. use a constant instead.