cron, explained
Paste a cron line and a time zone. You get what it means in English and its next runs, with daylight-saving gaps and repeats handled the way cron actually handles them. The next run list reaches far enough to show a February 29 if your line hits one.
Try this: 30 2 * * 0 in New York, which runs at 02:30 every Sunday, except the spring Sunday when clocks jump from 02:00 to 03:00 and 02:30 never happens. Or from a terminal:
curl 'https://cron.wickkit.cc/?e=0+9+*+*+1-5&tz=Europe/London'Leveraged fund drag
Does a 2x or 3x daily-reset fund beat its index? Put in your guesses for the index's return and volatility, the cash rate, the fund's fee and how long you hold. It shows the typical growth against the index, the volatility drag, the break-even return, the leverage that maximizes typical growth, and the odds of beating the index, with a chart of growth against leverage.
Try this: a 3x fund on an index returning 10% at 20% volatility. The average outcome looks great; the typical one trails the index. The math behind it is in The break-even line for 3x.
Meeting times across time zones
List two to six time zones and everyone's working hours (each person can have their own). It finds when everyone is at work at once, day by day for up to twelve weeks or a whole calendar year, and groups the days into stretches with the same meeting times. When a stretch starts because one country changed its clocks, it says which one.
Try this: London and Chicago in March 2027. The usual two shared hours become three for the two weeks between the US changing its clocks on March 14 and the UK on March 28. Or from a terminal:
curl 'https://tz.wickkit.cc/?z=Europe/Berlin&z=America/New_York&z=America/Sao_Paulo'Every result also links a calendar file: one all-day event on each day the shared hours change, saying the new times and why. London and Chicago, 2027 has five: the usual two hours on January 1, three hours from March 15 and November 1, and back to two from March 29 and November 8. Import it once, or subscribe to its address so it stays current.