Jin-chung> Hi: I have encountered several problems with plot_date.
    Jin-chung> I am using 0.60.1 (maybe fixed in 0.60.2?) on Solaris.

    Jin-chung> (1) If I put a smaller number as one of the dates (as
    Jin-chung> seconds), it raises the "before the epoch" error. But
    Jin-chung> I think plot_date should accomodate dates earlier than
    Jin-chung> 1970.

Yes, this is on the goals page - when I implemented the dates module,
I wanted to be able to support python2.2, and thus fell back on the
time module which is based on the epoch. It's a limitation that needs
to be addressed. On possibility is to require python2.3 for datetime
support - probably better is to use datetime and an earlier epoch
where available.

    Jin-chung> (2) After the error in (1) happens, even if I put
    Jin-chung> "legal" dates and run plot_date again, it still issues
    Jin-chung> the same error. It seems there is some kind of switch
    Jin-chung> needs to be reset.

Does cla() help - normally all plot data is kept around until the axes
are cleared. This happens by default is axes.hold is False in rc or
if you manually set

  >>> hold(False)

If you still have the problem after the axes are cleared, let me know
because then it's a bug.

    Jin-chung> (3) if, e.g. t=[1.e8, 1.1e8], the x-axis tick labels
    Jin-chung> are crowded.

This appears to be fixed in 0.61 with Peter Groszkowski
MultiWeekLocator submission.